Doppler type ultrasonic flowmeter, flow rate measuring method using doppler type ultrasonic flowmeter and flow rate measuring program used in this doppler type ultrasonic flowmeter

ABSTRACT

A doppler ultrasonic flowmeter including: an ultrasonic transmission member for casting ultrasonic pulses onto the fluid within a fluid tube, which is to be measured, along a measurement line from an ultrasonic transducer, a flow-speed distribution measurement unit for receiving ultrasonic echoes reflected from the measurement region due to ultrasonic pulses cast onto the fluid to be measured so as to measure the flow-speed distribution of the fluid to be measured in the measurement region; a flow measurement unit for measuring the flow of the fluid to be measured; and a transducer position adjusting mechanism for adjusting the relative position of a pair of ultrasonic transducers serving as the ultrasonic transmission member, a first transducer and a second transducer, which are disposed away one from another along the axial direction of a fluid tube.

TECHNICAL FIELD

The present invention relates to a doppler ultrasonic flowmeter formeasuring the flow-speed distribution of a fluid and the flow thereofusing ultrasonic pulses, a flow measurement method with the dopplerultrasonic flowmeter, and a flow measurement program thereof,particularly to a doppler ultrasonic flowmeter having a function formeasuring the flow-speed distribution of various fluids and flow thereofin a non-contact manner, a flow measurement method with the dopplerultrasonic flowmeter, and a flow measurement program thereof.

BACKGROUND ART

As a conventional technique, a doppler ultrasonic flowmeter using theultrasonic pulsed doppler method has been known as disclosed in JapaneseUnexamined Patent Application Publication No. 2000-97742.

The doppler ultrasonic flowmeter has a configuration wherein ultrasonicpulses are cast from a transducer onto a measurement line within a flowtube, ultrasonic echo signals, i.e., the reflected-wave signals fromsuspended fine particles in a fluid flowing in the fluid tube areanalyzed so as to calculate the flow-speed distribution and the flow ofthe fluid flowing along the measurement line based upon the positionsand velocities of the suspended fine particles. The measurement line isformed by an ultrasonic-pulse beam cast from the transducer.

The doppler ultrasonic flowmeter may be applied to an opaque fluid andan opaque-fluid tube, as well as having the advantage of measuring theflow of a fluid flowing a fluid tube in a non-contact manner.Furthermore, the doppler ultrasonic flowmeter has the advantage ofmeasurement of the flow-speed distribution of an opaque fluid and theflow thereof, e.g., measurement of the flow of liquid metal such asmercury, sodium, and so forth, as well as having functions for measuringthe flow-speed distribution and the flow of a fluid flowing in the flowtube with measurement along the measurement line.

The doppler ultrasonic flowmeter has the advantage of detecting changein the flow-speed distribution over time along the measurement lineformed by the ultrasonic pulses cast onto the fluid from the transducer,and accordingly, it is hoped that the doppler ultrasonic flowmeter canbe applied to measurement of a transient flow of a fluid flowing throughthe flow tube, and measurement of the flow-speed distribution andmeasurement of the flow in a turbulent situation.

An arrangement example of the ultrasonic flow-speed distribution meterand the ultrasonic flowmeter described above is disclosed in JapaneseUnexamined Patent Application Publication No. 2000-97742.

Measurement with the conventional doppler ultrasonic flowmeters is madeunder the assumption of existence of reflected ultrasonic echoes due toreflection from bubbles or particles contained in a fluid which is to bemeasured. Accordingly, in some cases, extremely unstable flow of thefluid which is to be measured leads to irregularities in the measurementresults of the flow-speed distribution due to irregularities in densityof bubbles or the like. Furthermore, with the conventional dopplerultrasonic flowmeters, measurement of the flow is made based upon themeasurement results of the flow-speed distribution. Accordingly, suchirregularities in the flow-speed distribution affect computation of theflow, resulting in irregularities in the measurement results of theflow, as well.

Furthermore, the conventional doppler ultrasonic flowmeter has afunction for receiving ultrasonic echoes at 128 positions at best,giving consideration to a tradeoff between responsibility of measurementof the flow which changes in a short period of time and the performanceof the hardware of the conventional doppler ultrasonic flowmeter. Inthis case, the minimum interval (which will be referred to as “channeldistance” hereafter) between the measurement points for measuring theultrasonic echoes matches the value obtained by dividing the ultrasonicspeed Cw in the fluid to be measured, by twice the basic frequency f₀ ofthe ultrasonic pulse.

Accordingly, with the conventional doppler ultrasonic flowmeteremploying such a channel distance, the maximum distance of themeasurement line matches 128 times the minimum channel distance, leadingto a problem that measurement of the flow-speed distribution cannot bemade over the entire tube in a case wherein the fluid tube is formedwith a greater diameter than the aforementioned measurement line.

On the other hand, the ultrasonic speed Cw in the fluid which is to bemeasured, the basic frequency f₀ of the ultrasonic pulses, and theincident angle α of the ultrasonic pulse, are adjusted based upon thekind of the fluid which is to be measured, the thickness and material ofthe tube, so as to make optimum measurement. Accordingly, conventionaldoppler ultrasonic flowmeters require preliminary measurement fordetermining the optimum settings suitable for the object which is to bemeasured, which is troublesome. This leads to low evaluation of ease ofuse, although the conventional doppler ultrasonic flowmeter has theadvantage of making measurement while suppressing error without “flowcorrection coefficients”.

On the other hand, an arrangement may be made wherein the kind of thehardware is varied corresponding to the object to be measured and themeasurement range, e.g., the doppler ultrasonic flowmeter may includemultiple kinds of hardware so as to handle various tube size and variousrange of the maximum flow speed. However, such a configuration isundesirable from the perspective of design, costs, and the like.

On the other hand, an arrangement may be made wherein measurement ismade at a greater number of measurement positions than with theaforementioned one so as to make measurement over a greater length thanwith the conventional one. However, such configuration is restricted bythe performance of the hardware, costs, and so forth, from theperspective of responsibility of the measurement of the flow whichchanges in a short period of time. Even if the problems of the hardwareperformance and costs are solved in the future, such configuration isundesirable since such configuration is overspeced for the measurementrange in which measurement can be made with the conventional dopplerultrasonic flowmeters.

On the other hand, the conventional doppler ultrasonic flowmeters have aconfiguration wherein measurement can be made even if a part of thefluid flows backward, i.e., a part of the fluid flows at a negativevelocity. However, in actual measurement, in a case wherein the fluidflows at a sufficient flow speed, hardly any fluid flows backward.Accordingly, an arrangement may be made wherein only the forward flow ismeasured on the assumption that there is no backward flow in order toextend the measurement range of the flow speed. However, suchconfiguration has a problem that determination cannot be made whether ornot a backward flow occurs.

Accordingly, it is an object of the present invention to provide adoppler ultrasonic flowmeter for making more correct measurement of theflow-speed distribution or measurement of the flow regardless ofirregularities in the measurement results of the flow-speeddistribution, a flow-measurement method using the doppler ultrasonicflowmeter, and a flow-measurement program employed for the dopplerultrasonic flowmeter.

Furthermore, it is another object of the present invention to provide adoppler ultrasonic flowmeter having a function for automaticallycalculating setting values corresponding to the properties of the objectto be measured, a flow-measurement method using the doppler ultrasonicflowmeter, and a flow-measurement program employed for the dopplerultrasonic flowmeter.

Furthermore, it is another object of the present invention to provide adoppler ultrasonic flowmeter having a greater measurement range thanwith the conventional one without extending the performance of thehardware thereof, a flow-measurement method using the doppler ultrasonicflowmeter, and a flow-measurement program employed for the dopplerultrasonic flowmeter.

Furthermore, it is another object of the present invention to provide adoppler ultrasonic flowmeter having functions for extending themeasurement range for the flow speed in a case wherein there is no flowat a negative velocity while detecting whether or not there is any flowat a negative velocity, a flow-measurement method using the dopplerultrasonic flowmeter, and a flow-measurement program employed for thedoppler ultrasonic flowmeter.

DISCLOSURE OF INVENTION

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 1comprises: an ultrasonic transmission member for casting ultrasonicpulses with a predetermined frequency onto the fluid within a tube,which is to be measured, along a measurement line from an ultrasonictransducer; a flow-speed distribution measurement unit for receivingultrasonic echoes reflected from the measurement region due toultrasonic pulses cast onto the fluid to be measured so as to measurethe flow-speed distribution of the fluid to be measured in themeasurement region; a flow measurement unit for measuring the flow ofthe fluid to be measured in the measurement region based upon theflow-speed distribution of the fluid to be measured; and a frequencyselecting/setting member for automatically selecting the optimumfrequency, i.e., the basic frequency f₀ which causes the resonanttransmission phenomenon with regard to the tube wall of a fluid tubewithin which the fluid to be measured flows, with the ultrasonictransmission member having a configuration for emitting ultrasonicpulses with the optimum frequency selected by the frequencyselecting/setting member.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 2comprises: an ultrasonic transmission member for casting ultrasonicpulses with a predetermined frequency onto the fluid within a fluidtube, which is to be measured, along a measurement line from anultrasonic transducer; a flow-speed distribution measurement unit forreceiving ultrasonic echoes reflected from the measurement region due toultrasonic pulses cast onto the fluid to be measured so as to measurethe flow-speed distribution of the fluid to be measured in themeasurement region; a flow measurement unit for measuring the flow ofthe fluid to be measured in the measurement region based upon theflow-speed distribution of the fluid to be measured; and an incidentangle adjusting/setting member for adjusting and setting the incidentangle of the ultrasonic pulses cast from the ultrasonic transducer intothe fluid to be measured, with the incident angle adjusting/settingmember having a configuration for adjusting and setting the position andthe direction of the ultrasonic transducer such that the ultrasonicpulses are cast onto the fluid tube with an incident angle which causesthe resonant transmission phenomenon with regard to the tube wall of thefluid tube.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 3comprises: an ultrasonic transmission member for casting ultrasonicpulses with a predetermined frequency onto the fluid within a fluidtube, which is to be measured, along a measurement line from anultrasonic transducer; a flow-speed distribution measurement unit forreceiving ultrasonic echoes reflected from the measurement region due toultrasonic pulses cast onto the fluid to be measured so as to measurethe flow-speed distribution of the fluid to be measured in themeasurement region; a flow measurement unit for measuring the flow ofthe fluid to be measured in the measurement region based upon theflow-speed distribution of the fluid to be measured; and a transducerposition adjusting mechanism for adjusting the relative position of apair of ultrasonic transducers serving as the ultrasonic transmissionmember, i.e., a first transducer and a second transducer, which aredisposed away one from another along the axial direction of a fluidtube, with the transducer position adjusting mechanism having aconfiguration for adjusting the position of the pair of transducerswhile maintaining the positional relation thereof such that theultrasonic pulse beam cast from the first transducer and the ultrasonicpulse beam cast from the second transducer are orthogonal one to anotherin the measurement region within the fluid tube.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 4comprises: a first reflected-wave receiver and a second reflected-wavereceiver for receiving ultrasonic echoes, i.e., the reflected waves fromthe measurement region of the fluid tube due to ultrasonic pulses castfrom the first transducer and the second transducer; a velocity-vectorcalculating member for calculating the velocity vectors in the directionof the ultrasonic measurement lines of the first reflected-wave receiverand the second reflected-wave receiver based upon the magnitude ofultrasonic echoes received by the first reflected-wave receiver and thesecond reflected-wave receiver, respectively; and a flow-speed vectorcalculating member for calculating the flow-speed vector of the fluid tobe measured, by calculating the vector sum of the velocity vectorscalculated by the velocity vector calculating member, with theflow-speed distribution measurement unit calculating the flow-speeddistribution based upon the flow-speed vectors, and with the flowmeasurement unit computing the flow of the fluid to be measured, basedupon the flow-speed distribution.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 5 acomprises flow-speed distribution calculating member for calculating theflow-speed distribution of the fluid to be measured, within themeasurement region, with the flow-speed distribution calculating membercomprising: a flow-speed distribution calculating element forcalculating the flow-speed distribution of the fluid to be measured,within the fluid tube; a center position-detecting element for detectingthe center position of the fluid tube; and an area selecting element forselecting an area within the fluid tube where the flow-speeddistribution is calculated, in units of division area; the area of thefluid tube being divided at the center position into two division areas,and with the flow-speed distribution measurement unit computing theflow-speed distribution for one of the division areas, which has beenselected by the area selecting element, and estimate the flow-speeddistribution of the fluid to be measured, in the measurement region, onthe assumption that the flow-speed distribution is symmetrical withregard to the center position.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 6comprises a flow-speed distribution calculating member for calculatingthe flow-speed distribution of the fluid to be measured, within themeasurement region, with the flow-speed distribution calculating membercomprising: a flow-speed distribution calculating element forcalculating the flow-speed distribution of the fluid to be measured,within the measurement; a center position detecting element fordetecting the center position of the fluid tube; and an automatic areaselecting element for automatically selecting an area within the fluidtube where the flow-speed distribution is calculated, in units ofdivision area; the area of the fluid tube being divided at the centerposition into two division areas, and with the flow-speed distributionmeasurement unit computing the flow-speed distribution for one of thedivision areas, which has been selected by the automatic area selectingelement, and estimate the flow-speed distribution of the fluid to bemeasured, in the measurement region, on the assumption that theflow-speed distribution is symmetrical with regard to the centerposition.

Note that the aforementioned automatic area selecting element selects anarea where the flow-speed distribution of the fluid to be measuredexhibits sufficient continuity over the area including the measurementpoints near the inner wall of the tube. Furthermore, the automatic areaselecting element employs algorithm having a smoothing function such asspline processing, thereby selecting an area with a smooth boundary.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 7comprises: an ultrasonic transmission member for casting ultrasonicpulses with an emission frequency of f₀ from the ultrasonic transducerinto the fluid to be measured, within the fluid tube, along themeasurement line with an incident angle α; a flow-speed distributionmeasurement unit for receiving ultrasonic echoes reflected from themeasurement region due to ultrasonic pulses cast onto the fluid to bemeasured, with a pulse repetition frequency f_(PRF), so as to measurethe flow-speed distribution of the fluid to be measured within themeasurement region; a flow measurement unit for computing the flow ofthe fluid to be measured, within the measurement region, based upon theflow-speed distribution of the fluid to be measured; and anoptimum-value calculating member for automatically calculating theoptimum value used for adjustment of measurement, which depends upon theproperties of the object to be measured.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 8comprises: an ultrasonic transmission member for casting ultrasonicpulses with an emission frequency of f₀ from the ultrasonic transducerinto the fluid to be measured, within the fluid tube, along themeasurement line with an incident angle α; a flow-speed distributionmeasurement unit for receiving ultrasonic echoes reflected from themeasurement region due to ultrasonic pulses cast onto the fluid to bemeasured, with a pulse repetition frequency f_(PRF), so as to measurethe flow-speed distribution of the fluid to be measured within themeasurement region; a flow measurement unit for computing the flow ofthe fluid to be measured, within the measurement region, based upon theflow-speed distribution of the fluid to be measured; and anoptimum-value calculating member for automatically calculating theoptimum value used for adjustment of measurement, which depends upon theproperties of the object to be measured, with the optimum-valuecalculating member comprising: a data input element for inputting thetube diameter Di of the fluid tube, the ultrasonic wave speed Cw in thefluid to be measured, and the incident angle α of the ultrasonic pulses;a maximum flow-speed calculating element for calculating the maximumflow speed V based upon the flow-speed distribution calculated by theflow-speed distribution calculating member; a normalized-speedcalculating element for calculating the normalized speed V₀ by dividingthe calculated maximum flow speed V by the ultrasonic wave speed Cw inthe fluid to be measured; a normalized-frequency calculating element forcalculating the normalized frequency F₀ by dividing the pulse repetitionfrequency f_(PRF) by the emission frequency f₀; and a frequency settingelement for resetting the emission frequency to an emission frequency f₁so as to satisfy the following expressions: F₀≧4V₀·sin α; andf_(PRF)≦Cw/2Di, with the flow-speed distribution measurement unitreceiving ultrasonic echoes with the updated emission frequency f₁ so asto measure the flow-speed distribution.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 9comprises: an ultrasonic transmission member for casting ultrasonicpulses with an emission frequency of f₀ from the ultrasonic transducerinto the fluid to be measured, within the fluid tube, along themeasurement line with an incident angle α; a flow-speed distributionmeasurement unit for receiving ultrasonic echoes reflected from themeasurement region due to ultrasonic pulses cast onto the fluid to bemeasured, with a pulse repetition frequency f_(PRF), so as to measurethe flow-speed distribution of the fluid to be measured within themeasurement region; a flow measurement unit for computing the flow ofthe fluid to be measured, within the measurement region, based upon theflow-speed distribution of the fluid to be measured; and anoptimum-value calculating member for automatically calculating theoptimum value used for adjustment of measurement, which depends upon theproperties of the object to be measured, with the optimum-valuecalculating member comprising: a data input element for inputting thetube diameter Di of the fluid tube, the ultrasonic wave speed Cw in thefluid to be measured, and the incident angle α of the ultrasonic pulses;a maximum flow-speed calculating element for calculating the maximumflow speed V based upon the flow-speed distribution calculated by theflow-speed distribution calculating member; a normalized-speedcalculating element for calculating the normalized speed V₀ by dividingthe calculated maximum flow speed V by the ultrasonic wave speed Cw inthe fluid to be measured; a normalized-frequency calculating element forcalculating the normalized frequency F₀ by dividing the pulse repetitionfrequency f_(PRF) by the emission frequency f₀; and an incident anglesetting element for reset the incident angle of the ultrasonic pulses toan incident angle α1 so as to satisfy the following expressions:F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di, with the flow-speed distributionmeasurement unit receiving ultrasonic echoes due to ultrasonic pulsescast with the updated incident angle α1 so as to measure the flow-speeddistribution.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 10comprises: an ultrasonic transmission member for casting ultrasonicpulses with a predetermined frequency onto the fluid within a fluidtube, which is to be measured, along a measurement line from anultrasonic transducer; a flow-speed distribution measurement unit forreceiving ultrasonic echoes reflected from the measurement region due toultrasonic pulses cast onto the fluid to be measured so as to measurethe flow-speed distribution of the fluid to be measured in themeasurement region; a flow measurement unit for measuring the flow ofthe fluid to be measured in the measurement region based upon theflow-speed distribution of the fluid to be measured; a channel distancecomputing member for computing the minimum channel distance based uponthe frequency of the ultrasonic pulses and the speed thereof; ameasurement range display member for displaying the measurement rangecalculated based upon the minimum channel distance; and a channeldistance change/setting member for changing the channel distance to avalue obtained by multiplying the minimum channel distance by an integeraccording to instructions from the user, with the flow-speeddistribution measurement unit making measurement of the flow-speeddistribution with the channel distance thus determined.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 11comprises: an ultrasonic transmission member for casting ultrasonicpulses with a predetermined frequency onto the fluid within a fluidtube, which is to be measured, along a measurement line from anultrasonic transducer; a flow-speed distribution measurement unit forreceiving ultrasonic echoes reflected from the measurement region due toultrasonic pulses cast onto the fluid to be measured so as to measurethe flow-speed distribution of the fluid to be measured in themeasurement region; a flow measurement unit for computing the flow ofthe fluid to be measured in the measurement region based upon theflow-speed distribution of the fluid to be measured; a channel distancecomputing member for computing the minimum channel distance based uponthe frequency of the ultrasonic pulses and the speed thereof; and anautomatic channel distance change/determination member for determiningwhether or not the channel distance is changed to a value obtained bymultiplying the minimum channel distance by an integer, according to therequired measurement range determined based upon the input data of theinner diameter of the fluid tube within which the fluid to be measuredflows, and so forth, with the flow-speed distribution measurement unitmaking measurement of the flow-speed distribution with the channeldistance thus determined.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 12comprises: an ultrasonic transmission member for casting ultrasonicpulses with a predetermined frequency onto the fluid within a tube,which is to be measured, along a measurement line from an ultrasonictransducer; a flow-speed distribution measurement unit for receivingultrasonic echoes reflected from the measurement region due toultrasonic pulses cast onto the fluid to be measured so as to measurethe flow-speed distribution of the fluid to be measured in themeasurement region; a flow measurement unit for computing the flow ofthe fluid to be measured in the measurement region based upon theflow-speed distribution of the fluid to be measured; a flow-speeddistribution output member for outputting the relation between theflow-speed distribution of the fluid to be measured in the measurementregion and the distance in the direction of the measurement line in theform of an image on a screen; a flow-speed zero-point display member forsuperimposing the zero points each of which represent the flow speed ofzero, on the flow-speed distribution output by the flow-speeddistribution output member, in the form of a continuous line; and aflow-speed measurement range switching member which allows the user toswitch the measurement range between the normal measurement range andthe double-measurement-range, thereby enabling measurement of thepositive flow speed in a measurement range twice that of the normalmeasurement range, according to the selection of the user. With such aconfiguration, in the event that the user has requested the flow-speedmeasurement range switching member to switch the flow-speed measurementrange, the flow-speed distribution output member outputs the flow-speeddistribution in the positive range alone, as well as measuring theflow-speed distribution with a measurement range twice that of thenormal measurement mode.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 13comprises: an ultrasonic transmission member for casting ultrasonicpulses with a predetermined frequency onto the fluid within a fluidtube, which is to be measured, along a measurement line from anultrasonic transducer; a flow-speed distribution measurement unit forreceiving ultrasonic echoes reflected from the measurement region due toultrasonic pulses cast onto the fluid to be measured so as to measurethe flow-speed distribution of the fluid to be measured in themeasurement region; a flow measurement unit for computing the flow ofthe fluid to be measured in the measurement region based upon theflow-speed distribution of the fluid to be measured; a positive/negativedetermination member for determining whether or not the fluid-speeddistribution of the fluid to be measured contains any negativeflow-speed components in the measurement region; and a flow-speedmeasurement range switching member for switching the measurement rangeof the flow-speed distribution measurement unit to a measurement rangetwice that of the normal measurement mode, for measuring the positiveflow speed, in the event that determination has been made that theflow-speed distribution contains no negative flow-speed components. Withsuch a configuration, in the event that determination has been made thatthe flow-speed distribution contains no negative flow-speed components,the flow-speed distribution measurement unit make measurement of theflow-speed distribution with a measurement range twice that of thenormal measurement mode.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 14comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; and a flow measurement processing step for measuring the flow byfurther performing computation processing for the flow-speeddistribution data of the fluid to be measured, with the flow-speeddistribution measurement processing step comprising: a flow-speeddistribution calculating step for calculating the flow-speeddistribution data of the fluid to be measured, and the center positiondata of the fluid tube, by performing computation processing for theflow-speed distribution of the reflectors; a flow-speed distributiondata output step for outputting the flow-speed distribution data andcenter position data thus obtained in the flow-speed distributioncalculating step so as to be displayed on display; and an areadetermination step which allows the user to set a division area wherethe speed of the reflector groups is calculated in the flow-speeddistribution calculating step; the area of the fluid tube being dividedat the center position into two division areas.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 15comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; and a flow measurement processing step for measuring the flow byfurther performing computation processing for the flow-speeddistribution data of the fluid to be measured, with the flow-speeddistribution measurement processing step comprising: a flow-speeddistribution calculating step for calculating the flow-speeddistribution data of the fluid to be measured, and the center positiondata of the fluid tube, by performing computation processing for theflow-speed distribution of the reflectors; an automatic area selectingstep for automatically selecting a division area where the flow-speeddistribution is calculated using the reflector groups; the area of thefluid tube being divided at the center position into two division areas;and a flow-speed distribution data output step for outputting theflow-speed distribution data and the center position data obtained inthe flow-speed distribution calculating step and the automatic areaselecting step, so as to be displayed on display.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 16comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; an optimum-value setting step for calculating the optimum valuesof the basic frequency f₀, the pulse repetition frequency f_(PRF), andthe incident angle α; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured, with thereflector-group-speed calculating step comprising: an initial valueacquisition step for receiving the initial values of the basic frequencyf₀, the pulse repetition frequency f_(PRF), the incident angle α, at thestart of measurement; and a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of the number ofreflectors contained in the fluid to be measured, and with theoptimum-value setting step including an emission frequency reset stepfor resetting the emission frequency to an emission frequency f₁ so asto satisfy the following expressions: F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 17comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; an optimum-value setting step for calculating the optimum valuesof the basic frequency f₀, the pulse repetition frequency f_(PRF), andthe incident angle α; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured, with thereflector-group-speed calculating step comprising: an initial valueacquisition step for receiving the initial values of the basic frequencyf₀, the pulse repetition frequency f_(PRF), the incident angle α, at thestart of measurement; and a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of the number ofreflectors contained in the fluid to be measured, and with theoptimum-value setting step including an incident angle reset step forresetting the incident angle to α1 so as to satisfy the followingexpressions: F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 18comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a channel distance computing step for computing the minimumchannel distance based upon the frequency of the ultrasonic pulses andthe speed thereof; a measurement range display steps for displaying aGUI which allows the user to determine whether or not the channeldistance is set to a value obtained by multiplying the minimum channeldistance by an integer, thereby allowing the user to set the measurementregion to a value obtained by multiplying the minimum measurement regionby an integer; a channel distance changing step for changing the channeldistance to a value obtained by multiplying the minimum channel distanceby an integer, according to instructions of the user; and a flowmeasurement processing step for measuring the flow by further performingcomputation processing for the flow-speed distribution data of the fluidto be measured.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 19comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a channel distance computing step for computing the minimumchannel distance based upon the frequency of the ultrasonic pulses andthe speed thereof; a measurement range calculating step for calculatingthe measurement range based upon the minimum channel distance thuscomputed; a channel distance changing step having a function fordetermining whether or not the channel distance is to be set to a valueobtained by multiplying the minimum channel distance by an integer,thereby allowing the system to automatically change the channeldistance; and a flow measurement processing step for measuring the flowby further performing computation processing for theflow-speed-distribution data of the fluid to be measured.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 20comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a flow-speed distribution output step for outputting the relationbetween the flow-speed distribution of the fluid to be measured and thedistance in the direction of the measurement line ML, in the form of animage on a screen; a flow-speed zero-line display step for superimposinga fluid-speed zero line on the flow-speed distribution output in theform of an image on a screen in the flow-speed distribution output step;a flow-speed measurement range switching determination step which allowsthe user to determine whether or not the flow-speed measurement range isswitched; a flow-speed measurement range switching step for switchingthe flow-speed measurement range to twice that of the normal measurementrange, for measuring the positive flow speed according to theinstructions of the user; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 21comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a flow-speed range switching determination step which allows theuser to determine whether or not the flow-speed measurement range isswitched; a flow-speed distribution output step for outputting therelation between the flow-speed distribution of the fluid to bemeasured, and the distance in the direction of the measurement line ML,in the form of an image on a screen; a flow-speed zero-line display stepfor superimposing a flow-speed zero line on the flow-speed distributionoutput in the form of an image on a screen in the flow-speeddistribution output step; a flow-speed measurement range switching stepfor switching the flow-speed measurement range to twice that of thenormal measurement mode according to the instructions of the user formeasuring the positive flow speed; and a flow measurement processingstep for measuring the flow by further performing computation processingfor the flow-speed distribution data of the fluid to be measured.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 22comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a flow measurement processing step for measuring the flow byfurther performing computation processing for the flow-speeddistribution data of the fluid to be measured, with the flow-speeddistribution measurement processing step comprising: a flow-speeddistribution calculating step for calculating the flow-speeddistribution data of the fluid to be measured, and the center positiondata of the fluid tube, by performing computation processing for theflow-speed distribution of the reflectors; a flow-speed distributiondata output step for outputting the flow-speed distribution data andcenter position data thus obtained in the flow-speed distributioncalculating step so as to be displayed on display; and an areadetermination step which allows the user to set a division area wherethe speed of the reflector groups is calculated in the flow-speeddistribution calculating step; the area of the fluid tube being dividedat the center position into two division areas, and with a computerexecuting the reflector-group-speed calculating step, the flow-speeddistribution measurement processing step, and the flow measurementprocessing step, according to the program.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 23comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; and a flow measurement processing step for measuring the flow byfurther performing computation processing for the flow-speeddistribution data of the fluid to be measured, with the flow-speeddistribution measurement processing step comprising: a flow-speeddistribution calculating step for calculating the flow-speeddistribution data of the fluid to be measured, and the center positiondata of the fluid tube, by performing computation processing for theflow-speed distribution of the reflectors; an automatic area selectingstep for automatically selecting a division area where the flow-speeddistribution is calculated using the reflector groups; the area of thefluid tube being divided at the center position into two division areas;and a flow-speed distribution data output step for outputting theflow-speed distribution data and the center position data obtained inthe flow-speed distribution calculating step and the automatic areaselecting step, so as to be displayed on display, and with a computerexecuting the reflector-group-speed calculating step, the flow-speeddistribution measurement processing step, and the flow measurementprocessing step, according to the program.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 24comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; an optimum-value setting step for calculating the optimum valuesof the basic frequency f₀, the pulse repetition frequency f_(PRF), andthe incident angle α; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured, with thereflector-group-speed calculating step comprising: an initial valueacquisition step for receiving the initial values of the basic frequencyf₀, the pulse repetition frequency F_(PRF), the incident angle α, at thestart of measurement; and a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of the number ofreflectors contained in the fluid to be measured, and with theoptimum-value setting step including an emission frequency reset stepfor resetting the emission frequency to an emission frequency f₁ so asto satisfy the following expressions: F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di,and with a computer executing the reflector-group-speed calculatingstep, the flow-speed distribution measurement processing step, theoptimum-value setting step, and the flow measurement processing step,according to the program.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 25comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; an optimum-value setting step for calculating the optimum valuesof the basic frequency f₀, the pulse repetition frequency f_(PRF), andthe incident angle α; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured, with thereflector-group-speed calculating step comprising: an initial valueacquisition step for receiving the initial values of the basic frequencyf₀, the pulse repetition frequency f_(PRF), the incident angle α, at thestart of measurement; and a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of the number ofreflectors contained in the fluid to be measured, and with theoptimum-value setting step including an incident angle reset step forresetting the incident angle to α1 so as to satisfy the followingexpressions: F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di, and with a computerexecuting the reflector-group-speed calculating step, the flow-speeddistribution measurement processing step, the optimum-value settingstep, and the flow measurement processing step, according to theprogram.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 26comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a channel distance computing step for computing the minimumchannel distance based upon the frequency of the ultrasonic pulses andthe speed thereof; a measurement range display step for displaying a GUIwhich allows the user to determine whether or not the channel distanceis set to a value obtained by multiplying the minimum channel distanceby an integer, thereby allowing the user to set the measurement regionto a value obtained by multiplying the minimum measurement region by aninteger; a channel distance changing step for changing the channeldistance to a value obtained by multiplying the minimum channel distanceby an integer, according to instructions of the user; and a flowmeasurement processing step for measuring the flow by further performingcomputation processing for the flow-speed distribution data of the fluidto be measured, with a computer executing the steps according to theprogram.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 27comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a channel distance computing step for computing the minimumchannel distance based upon the frequency of the ultrasonic pulses andthe speed thereof; a measurement range calculating step for calculatingthe measurement range based upon the minimum channel distance thuscomputed; a channel distance changing step having a function fordetermining whether or not the channel distance is to be set to a valueobtained by multiplying the minimum channel distance by an integer,thereby allowing the system to automatically change the channeldistance; and a flow measurement processing step for measuring the flowby further performing computation processing for the flow-speeddistribution data of the fluid to be measured, with a computer executingthe steps according to the program.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 28comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a flow-speed distribution output step for outputting the relationbetween the flow-speed distribution of the fluid to be measured and thedistance in the direction of the measurement line ML, in the form of animage on a screen; a flow-speed zero-line display-step for superimposinga fluid-speed zero line on the flow-speed distribution output in theform of an image on a screen in the flow-speed distribution output step;a flow-speed measurement range switching determination step which allowsthe user to determine whether or not the flow-speed measurement range isswitched; a flow-speed measurement range switching step for switchingthe flow-speed measurement range to twice that of the normal measurementrange, for measuring the positive flow speed according to theinstructions of the user; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured, with acomputer executing the steps according to the program.

In order to solve the aforementioned problems, a doppler ultrasonicflowmeter according to the present invention disclosed in Claim 29comprises: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a flow-speed range switching determination step which allows theuser to determine whether or not the flow-speed measurement range isswitched; a flow-speed distribution output step for outputting therelation between the flow-speed distribution of the fluid to bemeasured, and the distance in the direction of the measurement line ML,in the form of an image on a screen; a flow-speed zero-line display stepfor superimposing a flow-speed zero line on the flow-speed distributionoutput in the form of an image on a screen in the flow-speeddistribution output step; a flow-speed measurement range switching stepfor switching the flow-speed measurement range to twice that of thenormal measurement mode according to the instructions of the user formeasuring the positive flow speed; and a flow measurement processingstep for measuring the flow by further performing computation processingfor the flow-speed distribution data of the fluid to be measured, with acomputer executing the steps according to the program.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram which shows a configuration of a dopplerultrasonic flowmeter according to a first embodiment of the presentinvention.

FIG. 2 is a schematic diagram which shows a basic configuration of acomputer included in a doppler ultrasonic flowmeter according to thepresent invention.

FIG. 3 is a schematic diagram which shows a configuration of a dopplerultrasonic flowmeter according to a second embodiment of the presentinvention.

FIG. 4 is a schematic explanatory diagram for describing a mechanism forcalculating the velocity component in the ultrasonic incident directionusing the doppler frequency with a doppler ultrasonic flowmeteraccording to a third embodiment of the present invention.

FIG. 5 is a diagram for describing a measurement mechanism of thedoppler ultrasonic flowmeter according to the third embodiment of thepresent invention.

FIG. 6 is a block diagram for describing signal processing performed bythe doppler ultrasonic flowmeter according to the third embodiment ofthe present invention.

FIG. 7 is a functional block diagram of a doppler ultrasonic flowmeteraccording to a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the fourth embodiment ofthe present invention.

FIG. 9 is a schematic diagram which shows an example of the flow-speeddistribution displayed on a display monitor, which allows the user toselect a division area where the flow-speed distribution is calculatedusing the reflector groups.

FIG. 10 is a functional block diagram of a doppler ultrasonic flowmeteraccording to a fifth embodiment of the present invention.

FIG. 11 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the fifth embodiment ofthe present invention.

FIG. 12 is a functional block diagram of a doppler ultrasonic flowmeteraccording to a sixth embodiment of the present invention.

FIG. 13 is an explanatory diagram for describing the conditions whichdetermine whether or not optimum measurement can be made with thedoppler ultrasonic flowmeter according to the sixth embodiment of thepresent invention, showing a region where optimum measurement can bemade and a region where optimum measurement cannot be made, wherein thehorizontal axis represents the normalized speed V*, and the verticalaxis represents the normalized frequency F*.

FIG. 14 is an explanatory diagram for describing the conditions whichdetermine whether or not optimum measurement can be made with thedoppler ultrasonic flowmeter according to the sixth embodiment of thepresent invention, showing a region where optimum measurement can bemade and a region where optimum measurement cannot be made, wherein thehorizontal axis represents the logarithm of Cw/Di, and the vertical axisrepresents the logarithm of the pulse repetition frequency (f_(PRF)).

FIG. 15 is an explanatory diagram for describing the conditions whichdetermine whether or not optimum measurement can be made with thedoppler ultrasonic flowmeter according to the sixth embodiment of thepresent invention, showing a region where optimum measurement can bemade and a region where optimum measurement cannot be made, as well asshowing typical kinds of tubes.

FIG. 16 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the sixth embodiment ofthe present invention.

FIG. 17 is a functional block diagram of a doppler ultrasonic flowmeteraccording to a seventh embodiment of the present invention.

FIG. 18 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the seventh embodiment ofthe present invention.

FIG. 19 is a functional block diagram of a doppler ultrasonic flowmeteraccording to an eighth embodiment of the present invention.

FIG. 20 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the eighth embodiment ofthe present invention.

FIG. 21 is a schematic explanatory diagram which shows an example of ascreen displayed on a display monitor in a measurement range displaystep of the ultrasonic flow measurement procedure of the dopplerultrasonic flowmeter according to the eighth embodiment of the presentinvention.

FIG. 22 is a functional block diagram of a doppler ultrasonic flowmeteraccording to a ninth embodiment of the present invention.

FIG. 23 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the ninth embodiment ofthe present invention.

FIG. 24 is a functional block diagram of a doppler ultrasonic flowmeteraccording to a tenth embodiment of the present invention.

FIG. 25(A) and FIG. 25(B) are diagrams which show examples of screensdisplayed on a display monitor, respectively displaying the relationbetween the flow-speed distribution data of the fluid to be measured,which has been output from the flow-speed distribution output member,and the distance in the measurement line ML, with the doppler ultrasonicflowmeter according to the tenth embodiment of the present invention.

FIG. 26 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the tenth embodiment ofthe present invention.

FIG. 27 is a functional block diagram of a doppler ultrasonic flowmeteraccording to an eleventh embodiment of the present invention.

FIG. 28 is an explanatory diagram for making description step by stepregarding the processing procedure of ultrasonic flow measurement withthe doppler ultrasonic flowmeter according to the eleventh embodiment ofthe present invention.

REFERENCE NUMERALS

10, 10A, 10B, 10C, 10D, 10E doppler ultrasonic flowmeter

11 fluid tube

12 fluid to be measured

13 ultrasonic flow-speed distribution data acquisition unit (Udflowunit)

14 computer

15 signal transmission cable

17 ultrasonic transmission member

18 flow-speed distribution data acquisition member

19 frequency selecting/setting member

20 ultrasonic transducer

21 oscillating amplifier

23 oscillator

24 emitter

25 ultrasonic reflector (reflector)

27 reflected-wave receiver

28 amplifier

29 A/D converter

30 flow-speed distribution data acquisition element

31 oscillation frequency varying element

32 basic frequency range setting element

33 reflected-wave magnitude extracting element

35 computation processing member

36 memory

37 storage member

38 input member

39 display monitor

40 interface member

41, 41A, 41B, 41C, 41D, 41E, 41F, 41G, 41H flow-measurement PG

43 contact medium

50, 50A doppler ultrasonic flowmeter

51 incident angle adjusting/setting member

52 incident angle adjusting mechanism

53 incident angle range setting member

54 reflected-wave magnitude extracting member

56 stepping motor

60 doppler ultrasonic flowmeter

61 ultrasonic transducer position adjusting mechanism

62 velocity-vector calculating member

63 flow-velocity vector calculating member

67, 67A flow-speed distribution-calculating member

68 flow calculating member

70 flow-speed distribution calculating element

71 center position detecting element

72 area selecting element

73 center line

74 area selection GUI

75 automatic area selecting element

77, 77A optimum value calculating member

78 data input element

79 maximum flow-speed calculating element

80 normalized flow-speed calculating element

81 normalized frequency calculating element

82 frequency setting element

84 incident angle setting element

87 channel distance computing member

88 measurement range display member

89 channel distance change/setting member

91 measurement range bar

92 flow-speed distribution display portion

93 channel distance change/determination dialog box

94 channel distance setting window

95 vertical cursor

97 channel distance automatic change/determination member

99 flow-speed distribution output member

100 flow-speed zero-point display member

101 flow-speed measurement range switching member

103 flow-speed zero line

104 flow-speed range switching GUI

106 positive/negative determination member

107 automatic flow-speed range switching member

BEST MODE FOR CARRYING OUT THE INVENTION

Description will be made regarding a doppler ultrasonic flowmeteraccording to an embodiment of the present invention with reference tothe accompanying drawings.

First Embodiment

FIG. 1 is a schematic diagram which shows a schematic configuration of adoppler ultrasonic flowmeter 10 according to a first embodiment of thepresent invention.

The doppler ultrasonic flowmeter 10 has a configuration for measuringthe flow-speed distribution of a fluid 12 (liquid or gas) which is to bemeasured, flowing within a fluid tube 11, thereby enabling real-timemeasurement of the flow over time. The doppler ultrasonic flowmeter 10comprises an ultrasonic flow-speed distribution data acquisition unit(which will be referred to as “Udflow unit” hereafter) 13 for makingmeasurement of the flow speed of the fluid 12 to be measured, flowingwithin the fluid tube 11, in a non-contact manner, and a computer 14 forcomputing the flow-speed distribution of the fluid 12 to be measuredbased upon the electric signals (data) received from the Udflow unit 13in order to calculate the flow of the fluid 12 to be measured, anddisplaying the measurement results thus obtained over time. Note thatthe Udflow unit 13 is electrically connected to the computer 14 througha signal transmission cable 15.

The Udflow unit 13 comprises an ultrasonic transmission member 17 fortransmitting ultrasonic pulses with a predetermined frequency (basicfrequency f₀) along the measurement line ML within the fluid 12 to bemeasured, an flow-speed distribution data acquisition member 18 forreceiving ultrasonic echoes reflected from the measurement region due tothe ultrasonic pulses cast onto the fluid 12 to be measured, andcalculating the flow-speed distribution of the fluid 12 which is to bemeasured in the measurement region in the form of the flow-speeddistribution data, and an frequency selecting/setting member 19 forautomatically selecting the ultrasonic frequency (which will be referredto as “optimum frequency” hereafter) which allows measurement of theflow-speed distribution of the fluid 12 to be measured, flowing withinthe fluid tube 11 or measurement of the flow thereof, with optimumefficiency.

The ultrasonic transmission member 17 comprises an ultrasonic transducer20 for oscillating ultrasonic pulses with a predetermined frequency, andan oscillating amplifier 21 serving as ultrasonic oscillation signalgenerating means for oscillating the ultrasonic transducer 20. Theoscillating amplifier 21 includes an oscillator 23 for generatingelectric signals with a predetermined basic frequency f₀, and an emitter24 for outputting pulse-shaped electric signals (which will be referredto as “ultrasonic oscillation signals” hereafter) at predetermined timeintervals (1/F_(rpf)) according to the electric signals received fromthe oscillator 23.

At the time of measurement of the flow-speed distribution of the fluid12 to be measured or measurement of the flow thereof, the ultrasonictransducer 20 receives ultrasonic oscillation signals with thepredetermined basic frequency f₀ from the oscillating amplifier 21serving as ultrasonic oscillation signal generating means. Uponreception of the pulse-shaped ultrasonic oscillation signals, theultrasonic transducer 20 oscillates ultrasonic pulses with the basicfrequency f₀, and casts the ultrasonic pulses thus oscillated onto thefluid 12 to be measured, along the measurement line ML. Note that theultrasonic pulses are cast with the pulse width of around 5 mm, forexample, in the form of a straight beam with an extremely smalldivergence angle.

The ultrasonic transducer 20 has the functions serving as ultrasonicreceiving means as well as the ultrasonic transmission member 17. Withthe present embodiment, the ultrasonic transducer 20 receives ultrasonicechoes due to reflection of incident ultrasonic pulses from one of agreat number of ultrasonic reflectors (which may be simply referred toas “reflector” hereafter) 25 contained in the fluid 12 which is to bemeasured. Note that examples serving as reflectors 25 include: bubbles,fine particles of a material such as aluminum or the like havingdifferent acoustic impedance from that of the fluid 12 to be measured,i.e., a foreign material, which are contained with high uniformity inthe fluid 12 to be measured.

The ultrasonic echoes received by the ultrasonic transducer 20 aretransmitted to a reflected-wave receiver 27 included in the Udflow unit13. The reflected-wave receiver 27 converts the ultrasonic echoes intoelectric signals. The electric signals (which will be referred to as“ultrasonic echo signals” hereafter) converted from the ultrasonicechoes are input to an amplifier 28 from the reflected-wave receiver 27.The electric signals are amplified by the amplifier 28, following whichthe electric signals are input to an analog-to-digital (which will bereferred to as “A/D” hereafter) converter 29.

Furthermore, the A/D converter 29 receives electric signals (which willbe referred to as “basic frequency signals” hereafter) with a basicfrequency f₀ from the oscillating amplifier 21. Accordingly, the A/Dconverter 29 converts the ultrasonic echo signals and the basicfrequency signals in the form of analog signals into those in the formof digital signals. Then, the digitized ultrasonic echo signals and thedigitized basic frequency signals are input to a speed-distribution dataacquisition element 30.

The speed-distribution data acquisition element 30 includes a processorfor performing computation processing, and has a function forcalculating change in the position corresponding to the doppler shiftbased upon the digitized ultrasonic echo signals and the digitized basicfrequency signals received from the A/D converter 29, each of which aretime-series data, more specifically, based upon the difference in thefrequency between both the aforementioned signals, thereby calculatingthe speed of a number of reflectors (which will be expediently referredto as “reflectors” or “reflector group” hereafter) 25 contained in thefluid 12 to be measured, along the measurement line ML. The measurementresults are corrected with regard to the tilt angle α, thereby measuringthe flow-speed distribution of the reflectors 25 on the cross-section ofthe fluid tube 11.

The speed of the reflectors 25 contained in the fluid 12 to be measuredis assumed to be the same as the flow speed of the fluid 12 to bemeasured. Accordingly, measuring the speed of the reflectors 25contained in the fluid 12 to be measured means measuring the flow speedof the fluid 12 to be measured. The flow-speed data of the reflectors 25thus obtained by computation processing is output from the flow-speeddistribution data acquisition element 30, and is input to the computer14 serving as flow-speed distribution calculating member and flowcalculating member through the signal transmission cable 15.

The computer 14 performs computation processing for the flow-speed dataof the reflectors 25 received from the flow-speed distribution dataacquisition element 30. First, the computer 14 performs flow-speeddistribution measurement processing step for calculating the flow-speeddistribution of the fluid 12 to be measured, and displaying thecalculation results on display included in the computer 14. Then, thecomputer 14 further performs flow measurement processing step forcomputing the flow thereof based upon the flow-speed distribution of thefluid 12 to be measured thus obtained, and displaying the calculationresults.

The frequency selecting/setting member 19 comprises an oscillationfrequency varying element 31 for inputting control signals to theoscillating amplifier 21 for controlling the oscillation frequency ofthe oscillating amplifier 21, a basic frequency range setting element 32for operating the oscillation frequency varying element 31 in apredetermined frequency range, e.g., in a frequency range of 200 kHz to4 MHz, the reflected-wave receiver 27 for receiving the ultrasonicechoes which are the reflected waves from the reflector 25 within thefluid tube 11, and outputting the ultrasonic echo signals converted fromthe ultrasonic echoes, the amplifier 28 for amplifying the ultrasonicecho signals received from the reflected-wave receiver 27, and areflected-wave magnitude extracting element 33 for extracting themagnitude of the ultrasonic echo signals received from the amplifier 28,and storing the extracted signal magnitude in memory included in thereflected-wave magnitude extraction element 33.

The frequency selecting/setting member 19 repeats processing forextracting and selecting the ultrasonic oscillation frequency by actionsof the reflected-wave magnitude extracting element 33, the oscillationfrequency varying element 31, and the like, thereby outputting controlsignals for automatically selecting and setting the optimum ultrasonicoscillation frequency suitable for the measurement. Then, the controlsignals output from the frequency selecting/setting member 19 is inputto the oscillating amplifier 21 in the form of feedback signals. Theoscillating amplifier 21 automatically selects and adjusts theoscillation frequency according to the control signals thus received.

In this case, the frequency selecting/setting member 19 automaticallyselects the optimum frequency, e.g., the basic frequency f₀ at whichresonant transmission occurs in the tube wall of the fluid tube 11within which the fluid 12 to be measured flows, for example, therebyallowing the ultrasonic transducer 20 to oscillate the ultrasonic pulseswith the optimum frequency. Specifically, the frequencyselecting/setting member 19 automatically selects the optimum frequencysuch that the value obtained by multiplying the half wavelength of theultrasonic pulses by an integer matches the tube thickness of the fluidtube 11 within which the fluid 12 to be measured flows. Theaforementioned method has been proposed based upon the fact that thefluid tube 11 formed with the wall thickness matching the value obtainedby multiplying the half wavelength of the selected ultrasonic pulsehaving the basic frequency of f₀ by an integer exhibits extremely hightransmissivity with regard to the ultrasonic pulses.

FIG. 2 is a schematic diagram which shows a basic schematicconfiguration of the computer 14. The computer 14 comprises acomputation processing member 35 such as a CPU, an MPU, or the like, forperforming computation processing, a memory 36 for temporarily storingelectronic data, a storage member 37 for recording and storing theelectronic data, a input member 38 which allow the user to inputinstructions, a display monitor 39 for displaying the computationresults, and an interface (which will be abbreviated to “I/F” hereafter)member 40 for electric connection between the computer 14 and externaldevices. Note that the storage member 37 stores a flow measurementprogram (“program” will be abbreviated to “PG” hereafter) 41 forallowing the computation processing member 35 to execute computationprocessing (including accessory computation processing) for calculatingthe flow-speed distribution of the fluid 12 to be measured and the flowthereof.

With the doppler ultrasonic flowmeter 10, the computer 14 executes theflow measurement PG 41. As a result, the computer 14 performs flow-speeddistribution measurement processing step, or a series of flow-speeddistribution measurement processing step and the flow measurementprocessing step, according to the flow measurement PG 41, and displaysthe measurement results of the flow-speed distribution of the fluid 12to be measured or the measurement results of the flow thereof on thedisplay monitor 39.

Note that in FIG. 1, reference numeral 43 denotes a contact medium forsmoothly transmitting the ultrasonic waves cast from the ultrasonictransducer 20 into the fluid tube 11. That is to say, the contact medium43 is provided for reducing the acoustic impedance for improvingtransmission of the ultrasonic pulses cast into the fluid tube 11 fromthe ultrasonic transducer 20, thereby improving acoustic switching.

While description has been made regarding the doppler ultrasonicflowmeter 10 having a configuration wherein the Udflow unit 13 iselectrically connected to the computer 14 through the signaltransmission cable 15, the present invention is not restricted to theaforementioned arrangement, rather, the Udflow unit 13 is connected tothe computer 14 via wireless communication.

While description has been made regarding an arrangement wherein theUdflow unit 13 includes the reflected-wave receiver 27 and theultrasonic transducer 20, an arrangement may be made wherein theultrasonic transducer 20 further has the functions serving as thereflected-wave receiver 27. While description has been made regarding anarrangement wherein the Udflow unit 13 includes the flow-speeddistribution data acquisition element 30, the present invention is notrestricted to the aforementioned arrangement, rather, an arrangement maybe made wherein the computer 14 has the functions serving as theflow-speed distribution data acquisition element 30 according tosoftware instructions.

With the doppler ultrasonic flowmeter 10 having a configuration as shownin FIG. 1, the fluid tube 11 is formed with the wall thickness matchingthe value obtained by multiplying the half wavelength of the ultrasonicpulses by an integer exhibits extremely improved transmissivity withregard to the ultrasonic waves at the interface of the fluid tube 11 dueto the resonant effects. The improved ultrasonic transmissivity withregard to the ultrasonic waves improves ultrasonic echo signals due toreflection from the reflectors contained in the fluid 12 to be measured.Accordingly, with the doppler ultrasonic flowmeter 10 according to thepresent embodiment, the ultrasonic transducer 20 oscillates theultrasonic pulses with the optimum basic frequency f₀ suitable for thewall thickness of the fluid tube 11 according to instructions from thefrequency selecting/setting member 19. this matter reduces decay of theultrasonic pulses along the ultrasonic path (path along the measurementline ML), as well as improving the ultrasonic transmissivity at theinterface of the fluid tube 11, thereby achieving sufficient magnitudeof the reflected waves.

Second Embodiment

FIG. 3 is a schematic diagram which shows a schematic configuration of adoppler ultrasonic flowmeter 50 according to a second embodiment of thepresent invention.

The doppler ultrasonic flowmeter 50 has a configuration for improvingthe signal-to-noise (which will be abbreviated to “S/N” hereafter) ratioof the reflected waves, but having no function for selecting and settingthe optimum frequency of the ultrasonic pulses cast into the fluid tube11.

In order to improve the S/N ratio of the reflected waves, an arrangementmay be made wherein the wall thickness of the fluid tube 11 is adjustedsuch that resonant transmission occurs. However, such a configurationfor adjusting the wall thickness of the fluid tube 11 is far frompractical. With the present embodiment, the mounting angle of theultrasonic transducer 20 is adjusted, thereby achieving the same effectsas with the aforementioned configuration for adjusting the wallthickness of the fluid tube 11.

The doppler ultrasonic flowmeter 50 has a function for adjusting theincident angle α of the ultrasonic pulses emitted from the ultrasonictransducer 20, according to instructions received from an incident angleadjusting/setting member 51, thereby automatically adjusting theincident angle of the ultrasonic pulses suitable for the wall thicknessof the fluid tube 11. Note that the same components as with the dopplerultrasonic flowmeter 10 described in the first embodiment are denoted bythe same reference numerals, and description thereof will be omitted.

The doppler ultrasonic flowmeter 50 shown in FIG. 3 includes theincident angle adjusting/setting member 51, instead of the frequencyselecting/setting member 19.

The incident angle adjusting/setting member 51 comprises the ultrasonictransducer 20 mounted on the fluid tube 11 from the outside with anadjustable mounting angle, an incident angle adjusting mechanism 52 foradjusting the incident angle α of the ultrasonic pulses cast from theultrasonic transducer 20, an incident angle range setting member 53 foroperating the incident angle adjusting mechanism 52 in a predeterminedangular range, e.g., in a range of an incident angle α of 5° to 45°, anda reflected-wave magnitude extracting member 54 for extracting themagnitude of the ultrasonic echoes from the ultrasonic echoes reflectedfrom the measurement region within the aforementioned fluid tube 11, andstoring the extracted results. Note that the magnitude of the ultrasonicechoes thus extracted and stored by the reflected-wave magnitudeextracting member 54 is input to the computer 14, and is displayed onthe display monitor 39.

The aforementioned incident angle adjusting/setting member 51 has theincident angle adjusting mechanism 52 for adjusting the incident angle αof the ultrasonic pulses in a range approximately 5° to 45°.Specifically, the incident angle adjusting mechanism 52 outputs controlsignals for automatically adjusting the mounting angle of the ultrasonictransducer 20 to be the optimum value. More specifically, the mountingangle of the ultrasonic transducer 20 is adjusted by driving a mountingangle adjusting mechanism such as a stepping motor 56 or the like, forexample, according to the control signals output from the incident angleadjusting mechanism 52.

The incident angle α of the ultrasonic pulses cast from the ultrasonictransducer 20 matches the angle between the ultrasonic pulse beam andthe line or the plane orthogonal to the tube surface of the fluid tube11. The incident angle of the ultrasonic pulses cast from the ultrasonictransducer 20 is adjusted by the incident angle adjusting/setting member51 such that resonant transmission occurs with regard to the wallthickness of the fluid tube 11, i.e., the optimum incident angle isselected.

The incident angle adjusting/setting member 51 has the functions forextracting the magnitude of the reflected waves by actions of thereflected-wave magnitude extracting member 54 while varying the incidentangle of the ultrasonic pulse cast from the ultrasonic transducer 20 inan incident angular range of approximately 5° to 45° according to thecontrol signals output from the incident angle adjusting mechanism 52,and storing the measurement results. The magnitude of the reflectedwaves stored in the reflected-wave magnitude extracting member 54 isinput to the incident angle adjusting/setting member 51 for repeatingextracting/selecting processing so as to automatically selecting theoptimum incident angle of the ultrasonic pulses, as well as beingdisplayed on the display monitor 39.

The doppler ultrasonic flowmeter 50 according to the present embodimenthas a configuration wherein the incident angle adjusting/setting member51 adjusts the incident angle of the ultrasonic pulses cast from theultrasonic transducer 20 to be the optimum incident angle, therebyachieving the same effects as with an arrangement wherein the wallthickness of the fluid tube 11 is changed, and thereby enablinghigh-precision measurement of the flow-speed distribution of the fluid12 to be measured, which flows within the fluid tube 11, and measurementof the flow thereof, using the ultrasonic pulses cast from theultrasonic transducer 20.

The distance of the propagation path within a material, i.e., thedistance of the ultrasonic propagation path within the fluid tube 11, iscontrolled by adjusting the incident angle (emission angle) of theultrasonic pulses cast from the ultrasonic transducer 20. With thepresent embodiment, the incident angle is adjusted such that thedistance of the ultrasonic propagation path matches a value obtained bymultiplying the half wavelength of the ultrasonic pulses by an integer.This causes the resonant transmission phenomenon with regard to the wallthickness of the fluid tube 11, thereby achieving the sufficient S/Nratio of the reflected waves, and thereby achieving the sufficientmagnitude of the ultrasonic echoes due to reflection. Thus, the dopplerultrasonic flowmeter 50 according to the present embodiment has theadvantage of enabling measurement of the flow-speed distribution of thefluid to be measured, which flows within the fluid tube 11, and themeasurement of the flow thereof, with high precision in anon-contact-manner.

While description has been made regarding an arrangement wherein thedoppler ultrasonic flowmeter 50 includes the incident angleadjusting/setting member 51, instead of the frequency selecting/settingmember 19, an arrangement may be made wherein a single dopplerultrasonic flowmeter includes a combination of the frequencyselecting/setting member 19 and the incident angle adjusting/settingmember 51. Such a configuration including a combination of the frequencyselecting/setting member 19 and the incident angle adjusting/settingmember 51 allows the doppler ultrasonic flowmeter to automaticallyselect and set the optimum frequency and the optimum incident angle in asimple manner.

The doppler ultrasonic flowmeters 10 and 50 shown in FIG. 1 and FIG. 3have a configuration for measuring the flow of the fluid to be measured,with the line measurement method for the flow-speed distribution usingthe doppler shift between the incident ultrasonic pulses and thereflected ultrasonic echo. Accordingly, in order to improve themeasurement precision, there is the need to increase the number of themeasurement lines ML, i.e., the number of the ultrasonic transducers 23.

In order to improve the measurement precision, an arrangement may bemade wherein the N ultrasonic transducers 20 are disposed on the tube 11at a predetermined pitch along the circumferential direction.Furthermore, each of the ultrasonic transducers 20 are tilted at a tiltangle α such that all the measurement lines pass through the axis of thetube 11, for example. Such a configuration enables real-time measurementof the flow of the fluid 12 to be measured, thereby enabling real-timedisplay of the flow thereof over time. In this case, the display monitor39 displays the flow-speed distribution of the fluid 12 to be measured,along each measurement line ML within the fluid tube 11, the flow-speeddistribution thereof on the cross-section of the tube, or measurementresults of the flow.

Third Embodiment

FIG. 4 through FIG. 6 are a schematic diagrams which show a schematicconfiguration of a doppler ultrasonic flowmeter 60 according to a thirdembodiment of the present invention.

As shown in FIG. 4, the doppler ultrasonic flowmeter 60 calculates thevelocity component V₂ of the fluid 12 to be measured, which flows withinthe flow tube 11, in the ultrasonic incident angle (ultrasonic emissionangle) direction, using the doppler frequency. That is to say, theflow-speed distribution is calculated along the measurement line MLbased upon the calculated doppler frequency with the line measurementmethod, thereby calculating the flow of the fluid 12 to be measured.

That is to say, with the doppler ultrasonic flowmeter 60, the velocityvector V₂ along the ultrasonic propagation path (measurement line ML) iscalculated based upon the doppler frequency. Then, the calculatedvelocity vector V₂ is divided by (sin α), thereby calculating thevelocity vector V₁ along the axis of the flow tube 11.

The doppler ultrasonic flowmeter 60 has the disadvantage that in a casewherein the fluid 12 to be measured does not flow in the directionparallel to the flow tube 11, i.e., in a case wherein a swirling flow ora non-parallel flow occurs within the fluid tube 11, the flow speedcannot be calculated with high precision. For example, let us consider acase wherein a bubble passes through the fluid tube 11 with the velocityvector V₃ as shown in FIG. 5. In this case, the velocity vector V₂ isobtained by projecting the velocity vector V₃ onto the ultrasonicpropagation path. However, the vector obtained by projecting thevelocity vector V₁ of the fluid 12 to be measured, onto the ultrasonicpropagation path, does not match the velocity vector V₂. Accordingly,the bubble passing through at such a velocity lead to false calculationresults of the flow speed of the fluid 12 to be measured, with positivedeviation, along the axial direction of the fluid tube 11.

In order to solve the aforementioned problem of false calculationresults of the flow speed, the doppler ultrasonic flowmeter 60 includestwo ultrasonic transducers 20 and 20 a mounted on the fluid tube 11.These two ultrasonic transducers 20 and 20 a are mounted orthogonal oneto another so as to measure the velocity vectors V₂ and V₄,respectively. Then, the vector sum of the velocity vectors V₂ and V₄ iscalculated, thereby obtaining the correct flow speed of the fluid 12 tobe measured or the flow speed of the bubble.

The doppler ultrasonic flowmeter 60 has a configuration wherein theposition of the ultrasonic transducer 20 a can be adjusted as to theother ultrasonic transducer 20 on the fluid tube 11 for measurement ofthe correct flow speed of the fluid 12 to be measured. Accordingly, thedoppler ultrasonic flowmeter 60 includes an ultrasonic transducerposition adjusting mechanism 61, and has a signal processingconfiguration shown in a signal processing block diagram in FIG. 6.

With the doppler ultrasonic flowmeter 60 shown in FIG. 6, the twoultrasonic transducers 20 and 20 a are disposed such that the incidentdirection of the ultrasonic pulses cast from the ultrasonic transducers20 and 20 a are orthogonal one to another within the fluid tube 11. Thatis to say, the doppler ultrasonic flowmeter 60 has a configurationwherein the ultrasonic pulse beams cast from the ultrasonic transducers20 and 20 a are orthogonal one to another in the measurement regionwithin the fluid tube 11.

The aforementioned doppler ultrasonic flowmeter 60 includes:reflected-wave receivers 27 and 27 a for receiving the ultrasonic echo,i.e., the reflected waves from the measurement region within the fluidtube 11 due to the ultrasonic pulses cast from the ultrasonictransducers 20 and 20 a; velocity-vector calculating member 62 and 62 afor calculating the velocity vectors in the directions of the ultrasonicmeasurement lines based upon the magnitude of the ultrasonic echoesreceived by the reflected-wave receivers 27 and 27 a; and aflow-velocity vector calculating member 63 for calculating theflow-speed vector of the fluid to be measured by making the vector sumof the velocity vectors calculated by the velocity vector calculatingmember 62 and 62 a. Thus, the doppler ultrasonic flowmeter 60 has afunction for calculating the flow of the fluid 12 to be measured basedupon the flow-speed distribution data sets along the measurement linesML within the fluid tube 11 calculated by the flow-velocity vectorcalculating member 63.

The ultrasonic echoes, i.e., the reflected waves reflected from themeasurement region within the fluid tube 11 due to the ultrasonic pulsescast from the ultrasonic transducers 20 and 20 a, are received by thereflected-wave receivers 27 and 27 a, respectively. Then, thevelocity-vector calculating member 62 and 62 a convert the magnitudesignals of the ultrasonic echoes received by the reflected-wavereceivers 27 and 27 a into the velocity vectors in the directions of themeasurement lines ML (directions of the ultrasonic propagation paths).Subsequently, the flow-velocity vector calculating member 63 calculatesthe vector sum of the velocity vectors in the directions of theultrasonic propagation paths thus obtained, thereby calculating thecorrect velocity vector, i.e., the correct flow speed of the fluid 12 tobe measured.

The aforementioned velocity vector calculating member 62 and 62 a, andthe flow-velocity vector calculating member 63, form a flow-speeddistribution data acquisition element 30A having the functions formeasuring the flow-speed distribution data sets of the fluid 12 to bemeasured, which flows within the fluid tube 11, along the directions ofthe ultrasonic propagation paths (measurement lines) ML, and calculatingthe flow of the fluid 12 to be measured by integrating the flow-speeddistribution data sets over the ultrasonic propagation paths.

Specifically, following calculation of the flow speed of a certainposition by the flow-velocity vector calculating member 63 of theflow-speed distribution data acquisition element 30A, the ultrasonictransducer 20 or 20 a is moved on the fluid tube 11 by actions of theultrasonic transducer position adjusting mechanism 61, thereby allowingacquisition of data at the next position. That is to say, the dopplerultrasonic flowmeter 60 has a configuration for measuring the flow-speeddistribution while moving the ultrasonic transducers 20 or 20 a byactions of the ultrasonic transducer position adjusting mechanism 61,thereby enabling measurement of the flow-speed distribution of the fluid12 to be measured over the ultrasonic propagation paths, and therebycalculating the correct flow thereof by calculation.

Fourth Embodiment

The present embodiment described below has generally the sameconfiguration as that of the doppler ultrasonic flowmeter 10 shown inFIG. 1, wherein the computer 14 executes the functions serving as adoppler ultrasonic flowmeter according to the flow measurement PG 41,i.e., a software program, stored in the storage member 37, incooperation with the Udflow unit 13 which is a hardware component,except for the configuration of the flow-measurement PG 41, leading todifference in the processing procedure or the functions provided for theuser.

Accordingly, description will be made hereafter with reference toconfiguration block diagrams alone. Furthermore, description will bemade in brief regarding the configuration of the doppler ultrasonicflowmeter. Note that with each embodiment, a different program, e.g., aflow-measurement PG 41A, is employed, instead of the flow-measurement PG41 shown in FIG. 2. Accordingly, description will be made hereafterregarding each embodiment with reference to FIG. 2, replacing theflow-measurement PG 41 with the flow-measurement PG 41A or the like.

FIG. 7 is a functional block diagram of a doppler ultrasonic flowmeter10A according to a fourth embodiment of the present invention.

The doppler ultrasonic flowmeter 10A shown in FIG. 7 has generally thesame configuration as that of the doppler ultrasonic flowmeter 10 shownin FIG. 1, wherein the computer 14 executes the functions serving as adoppler ultrasonic flowmeter according to the flow measurement PG 41A,i.e., a software program, stored in the storage member 37, incooperation with the Udflow unit 13 which is a hardware component.

As shown in FIG. 7, the doppler ultrasonic flowmeter 10A includes theUdflow unit 13 serving as the flow-speed data acquisition member 18 forcalculating the speed of the great number of reflectors 25 contained inthe fluid 12 to be measured in a reflector-group-speed calculating step,a flow-speed distribution calculating member 67 for measuring theflow-speed distribution of the fluid 12 to be measured by performingcomputation processing for the speed data of the reflectors 25 receivedfrom the Udflow unit 13 in a flow-speed distribution measurementprocessing step, and a flow calculating member 68 for measuring the flowof the fluid 12 to be measured by further performing computationprocessing for the speed distribution thereof.

With the doppler ultrasonic flowmeter 10A, the Udflow unit 13 serving asthe flow-speed data acquisition member 18 and the flow-speeddistribution calculating member 67 form a flow-speed distributionmeasurement unit. On the other hand, the flow calculating member 68makes measurement of the flow thereof based upon the flow-speeddistribution measurement results obtained by the flow-speed distributionmeasurement unit. That is to say, the Udflow unit 13, the flow-speeddistribution calculating member 67, and the flow calculating member 68,form a flow measurement unit. Note that the measurement results outputfrom at least one of the flow distribution calculating member 67 and theflow calculating member 68 are displayed on display such as the displaymonitor 39 of the computer 14, or the like.

The flow-speed distribution calculating member 67 of the dopplerultrasonic flowmeter 10A comprises a flow-speed distribution calculatingelement 70 for performing computation processing for the input speeddata of the reflectors 25 so as to calculate the flow-speed distributionof the fluid 12 to be measured within the fluid tube 11, acenter-position detecting element 71 for detecting the center of thefluid tube 11 in the radius direction, i.e., the center position of thefluid tube 11, and an area selecting element 72 for selecting one of twoareas (each of which will be referred to as “division area” hereafter)into which the area of the fluid tube 11 is divided at the centerposition; the flow-speed distribution being calculated using thereflectors 25 within the selected division area.

On the other hand, the flow calculating member 68 measures the flow ofthe fluid 12 to be measured by performing computation processing for theinput flow-speed distribution. Specifically, the flow of the fluid 12 tobe measured is calculated by integrating the input flow-speeddistribution over the radius direction (r direction) of the fluid tube11. The calculated value of the flow thereof is output from the flowcalculating member 68, and is displayed on display having a function fordisplaying the computation results.

Now, description will be made step by step regarding the ultrasonic flowmeasurement procedure for measurement of the flow of the fluid 12 to bemeasured performed by the doppler ultrasonic flowmeter 10A.

FIG. 8 is an explanatory diagram for making description step by stepregarding the ultrasonic flow measurement procedure (which is denoted by“first ultrasonic flow measurement procedure” in FIG. 8) for theultrasonic flow measurement method performed by the doppler ultrasonicflowmeter 10A.

As shown in FIG. 8, the ultrasonic flow measurement method comprises: areflector-group-speed calculating step (Step S1) for calculating thespeed of the number of reflectors 25 contained in the fluid 12 to bemeasured, and outputting the calculated flow-speed distribution of thereflectors 25 as the flow-speed distribution data from the Udflow unit13; a flow-speed distribution measurement processing step (Step S2 toStep S5) for performing computation processing for the input flow-speeddistribution data of the reflectors 25 so as to calculate the flow-speeddistribution of the fluid 12 to be measured; and a flow measurementprocessing step (Step S6 to Step S7) for further performing computationprocessing for the flow-speed distribution of the fluid 12 to bemeasured so as to calculate the flow thereof.

With the present ultrasonic flow measurement procedure, first, in StepS1, the Udflow unit 13 casts the ultrasonic pulses onto the fluid 12 tobe measured, and receives the ultrasonic echoes reflected by the fluid12 to be measured so as to calculate the flow-speed distribution of thereflectors 25 contained in the fluid 12 to be measured, whereby theflow-speed distribution data of the reflectors 25 is output. Then, theflow-speed distribution calculating member 67 receives the flow-speeddistribution data of the reflectors 25 thus output, and performs theflow-speed distribution measurement processing step (Step S2 throughStep S5).

The flow-speed distribution measurement processing step (Step S2 throughStep S5) comprises: a flow-speed distribution calculating step (Step S2)for calculating the flow-speed distribution data of the fluid 12 to bemeasured, and the center position data of the fluid tube 11, based uponthe flow-speed distribution data of the reflectors 25; a flow-speeddistribution data output step (Step S3) for outputting the flow-speeddistribution data and the center position data thus calculated todisplay for displaying such information; and an area selecting step(Step S5) for selecting one of the two division areas into which thearea of the fluid tube 11 has been divided at the center position,according to the selection of the user; the flow-speed distributionbeing calculated using the reflectors 25 within the selected area, inthe event of receiving a request to make selection of the reflectors 25for calculating the flow-speed distribution (i.e., in a case of “YES” inStep S4).

In the flow-speed distribution measurement processing step, first, inthe flow-speed distribution calculating step, i.e., Step S2, theflow-speed distribution and the center position of the fluid tube 11 arecalculated. Note that with the flow-speed distribution calculatingmember 67 shown in FIG. 7, a flow-speed distribution calculating element70 calculates the flow-speed distribution, and a center positiondetecting element 71 detects the center position.

The flow-speed distribution calculating element 70 calculates the speedof the reflector 25 for each position thereof contained in the fluid 12to be measured based upon the position and speed of each reflector 25,whereby flow speed is obtained for each position. On the other hand, thecenter position detecting element 71 detects the positions wheremultiple reflection of the ultrasonic echoes occurs, based upon thereceived ultrasonic echo signals, and determines the middle pointbetween the detected positions to be the center position, based upon thefact that multiple reflection of the ultrasonic echoes occurs on thewall face of the fluid tube 11. Upon completion of the calculation ofthe flow-speed distribution and the center position of the fluid tube 11by the flow-speed distribution calculating element 70 and the centerposition detecting element 71, the flow-speed distribution calculatingstep, i.e., Step S2 ends.

Upon completion of the flow-speed distribution calculating step in StepS2, the flow proceeds to Step S3, i.e., the flow-speed distribution dataoutput step, where the flow-speed distribution calculating element 70and the center position detecting element 71 output the flow-speeddistribution data and the center position data, respectively. Uponoutput of the flow-speed distribution data and the center position data,the flow-speed distribution data output step, i.e., Step S3 ends. Notethat the computation processing member 35 of the computer 14 calculatesboth the data sets thus output, i.e., the flow-speed distribution andthe center position, and display the calculation results on the displaymonitor 39.

Upon completion of the flow-speed distribution data output step, i.e.,completion of step S3, the user can confirm the flow-speed distributionof the fluid 12 to be measured, which has been measured with the dopplerultrasonic flowmeter 10A, by means of the display monitor 39. In theevent that the user has confirmed the flow-speed distribution of thefluid 12 to be measured, and has determined that there is no problemsuch as failure in measurement at any portion, or the like, (in theevent of “NO” in Step S4), the flow-speed distribution measurementprocessing step ends.

On the other hand, in the event that the user has determined that thereis a problem such as a problem that the flow speed is different betweenthe two division areas into which the cross-sectional area of the fluidtube is divided at the center position, but the flow speed of eachdivision area is not measured, the user can make a request through theinput member 38 of the computer 14 to select the area where theflow-speed distribution is to be calculated using the reflectors 25contained in the selected area.

The cross-sectional area of the fluid tube is divided at the centerposition into two areas, i.e., the division area close to the ultrasonictransducer 20 (which will be referred to as “close-side area” hereafter)and the division area away from the ultrasonic transducer 20, i.e., thefar-side division area (which will be referred to as “far-side area”hereafter), for measurement of the flow speed. The user can select thearea where the flow-speed distribution is to be calculated using thereflectors 25 contained in the selected area, from the three areas,i.e., the close-side area, the far-side area, and the entire area (boththe close area and the far-side area).

FIG. 9 is a schematic diagram which shows an example of the flow-speeddistribution displayed in the display monitor 39 with a function of thedivision area selection for selecting the area where the flow-speeddistribution is to be calculated using the reflectors 25.

As shown in FIG. 9, the user selects one of the choices through agraphical user interface (GUI), for example, whereby a desired divisionarea where the flow-speed distribution is to be calculated using thereflectors 25 is selected. In the example shown in FIG. 9, the leftregion in the drawing corresponds to the close-side area, and the rightregion in the drawing corresponds to the far-side area, with a centerline 73 in the drawing as the center position.

With the area selection GUI 74 displayed on the display monitor 39 shownin FIG. 9, the user selects one of “close-side” corresponding to theclose-side area, “far-side” corresponding to the far-side area, and“entire” corresponding to the entire area, whereby a desired divisionarea where the flow-speed distribution is to be calculated using thereflectors 25 is selected. In the example shown in FIG. 9, the entirearea is selected.

Upon the user making a request for selection of the area through theinput member 38 of the computer 14 (in the event of “YES” in Step S4),the flow proceeds to Step S5, i.e., the area selecting step, where thearea selecting element 72 selects a division area where the flow-speeddistribution is to be calculated using the reflectors 25 according tothe request from the user. Upon completion of the area selecting step,the flow proceeds to Step S2, following which the processing stepsfollowing the Step S2 are repeated.

In the event that the user has made a request for selecting the area,the flow-speed distribution is calculated for the selected area, i.e.,the close-side area or the far-side area, in Step S2, i.e., theflow-speed distribution calculating step. Note that the flow-speeddistribution is calculated on the assumption that the flow-speeddistribution within the fluid tube 11 is generally symmetrical withregard to the center position (tube axis). Upon calculation of theflow-speed distribution, the flow proceeds to Step S3, i.e., theflow-speed distribution data output step, where the calculatedflow-speed distribution is displayed on the monitor 39.

Upon completion of the flow-speed distribution measurement processingstep (Step S2 through Step S5), the flow proceeds to Step S6, followingwhich the flow calculating member 68 executes the flow measurementprocessing step (Step S6 and Step S7). Note that the flow measurementprocessing step comprises a flow calculating step (Step S6) and a flowdata output step (Step S7).

In the flow measurement processing step, first, the flow proceeds toStep S6, i.e., the flow calculating step. In the flow calculating step,the flow calculating member 68 receives the flow-speed distribution datacalculated in the flow-speed distribution measurement processing step,and integrate the received flow-speed distribution data over the radiusdirection (r direction) of the fluid tube 11, thereby calculating theflow of the fluid 12 to be measured. Upon calculation of the flow of thefluid 12 to be measured, Step S6 ends, following which the flow proceedsto Step S7, i.e., the flow data output step.

In the flow data output step, the flow calculation data calculated inthe flow calculating step is output as the flow measurement results.Upon output of the flow calculation data from the flow calculatingmember 68, Step S7 ends, i.e., the flow measurement processing stepends. Note that the flow measurement results output in Step S7 aresubjected to computation processing by the computation processing member35 of the computer 14, and are displayed on the display monitor 39 asshown in FIG. 9, for example.

Thus, the doppler ultrasonic flowmeter 10A according to the presentembodiment, the flow measurement method using the doppler ultrasonicflowmeter 10A, and the flow measurement program employed for the dopplerultrasonic flowmeter 10A, have a function for selecting an area wherecorrect measurement has been made, according to a request from the user,and calculating the flow-speed distribution for the area thus selected,thereby enabling more correct measurement of the flow-speed distributionregardless of irregularities in the measurement results of theflow-speed distribution. Furthermore, with the present embodiment, theflow thereof is computed based upon the correct measurement results ofthe flow-speed distribution, thereby enabling correct measurement of theflow thereof, as well.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 10 shown in FIG. 1, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41A stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the flow measurement PG 41A, i.e.,a software component, has the functions serving as the dopplerultrasonic flowmeter 10A, the present embodiment may be applied to thedoppler ultrasonic flowmeter 50 or the doppler ultrasonic flowmeter 60.

On the other hand, the present invention is not restricted to anarrangement wherein the measurement results of the flow are displayedalong with the flow-speed distribution as shown in FIG. 9, rather thedoppler ultrasonic flowmeter 10A may has a configuration wherein theflow is displayed separately from the flow-speed distribution.

Fifth Embodiment

FIG. 10 is a functional block diagram of a doppler ultrasonic flowmeter10B according to a fifth embodiment of the present invention.

The doppler ultrasonic flowmeter 10B shown in FIG. 10 has generally thesame configuration as that of the doppler ultrasonic flowmeter 10 shownin FIG. 1, wherein the computer 14 reads out and executes a flowmeasurement PG 41B stored in the storage member 37, whereby acombination of the Udflow unit 13, i.e., a hardware component unit, anda flow measurement PG 41B, i.e., a software component, has the functionsserving as the doppler ultrasonic flowmeter.

As shown in FIG. 10, the doppler ultrasonic flowmeter 10B has the sameconfiguration as that of the doppler ultrasonic flowmeter 10A, exceptfor a configuration including a flow-speed distribution calculatingmember 67A, instead of the flow-speed distribution calculating member67, and accordingly, the same components are denoted by the samereference numerals, and description thereof will be omitted. Note thatthe doppler ultrasonic flowmeter 10 according to the present embodimenthas the same configuration wherein the Udflow unit 13 serving as theflow-speed data acquisition-member 18 and the flow-speed distributioncalculating member 67A form the flow-speed distribution measurementunit, and the Udflow unit 13, the flow-speed distribution calculatingmember 67A, and the flow calculating member 68, form the flowmeasurement unit.

The flow-speed distribution calculating member 67A includes theflow-speed distribution calculating element 70 and the center positiondetecting element 71, and further include an automatic area selectingelement 75 for making automatic selection of the division area where theflow-speed distribution is to be calculated using the reflectors 25,instead of the area selecting element 72.

FIG. 11 is an explanatory diagram for describing the processingprocedure, i.e., the ultrasonic flow measurement procedure (which willbe denoted by “second ultrasonic flow measurement procedure” in FIG.11), step by step, employed for the doppler ultrasonic flowmeter 10B.

As shown in FIG. 11, the ultrasonic flow measurement procedure employedfor the doppler ultrasonic flowmeter 10B has generally the sameconfiguration as that of the ultrasonic flow measurement procedureemployed for the doppler ultrasonic flowmeter 10A shown in FIG. 8,except for the flow-speed distribution measurement processing step. Thatis to say, the difference therebetween is that the flow-speeddistribution measurement processing step according to the presentembodiment includes an automatic area selecting step for makingautomatic selection of the division area where the flow-speeddistribution is to be calculated using the reflectors 25, between theflow-speed distribution calculating step (Step S2) and the flow-speeddistribution data output step (Step S3).

As shown in FIG. 11, the ultrasonic flow measurement procedure employedfor the doppler ultrasonic flowmeter 10B comprises areflector-group-speed calculating step (Step S11), a flow-speeddistribution measurement processing step (Step S12 through Step S14),and a flow measurement processing step (Step S15). First, the flowproceeds to the reflector-group-speed calculating step (Step S11), theflow proceeds to the flow-speed distribution measurement processing step(Step S12 through Step S14), and the flow proceeds to the flowmeasurement processing step (Step S15).

That is to say, in the ultrasonic flow measurement procedure employedfor the doppler ultrasonic flowmeter 10B, first, the flow proceeds tothe reflector-group-speed calculating step (Step S11) having the samefunctions as with the reflector-group-speed calculating step (step S1)shown in FIG. 8, following which the flow proceeds to the flow-speeddistribution measurement processing step (Step S12 through Step S14).

Specifically, in the flow-speed distribution measurement processing step(Step S12 through Step S14), the flow proceeds to the flow-speeddistribution calculating step (Step S12) having the same functions aswith the flow-speed distribution calculating step (Step S2) shown inFIG. 8, following which the flow proceeds to Step S13, i.e., theautomatic area selecting step, where the flow-speed distributioncalculating member 67A makes automatic selection of the division areawhere the flow-speed distribution is to be calculated using thereflectors 25.

Upon automatic selection of the division area where the flow-speeddistribution is to be calculated using the reflectors 25 in theautomatic area selecting step, i.e., in Step S13, the flow proceeds toStep S14, i.e., the flow-speed distribution data output step, where theflow-speed distribution data and the center position data calculated inStep S12 and Step S13 are output for displaying the information on thedisplay monitor 39 or the like, whereby the flow-speed distribution dataoutput step, i.e., Step S14 ends.

Upon completion of the flow-speed distribution data output step, i.e.,Step S14, the flow proceeds to the flow measurement processing step(Step S15), where the flow calculating member 68 performs calculationprocessing. Note that the flow measurement processing step (Step S15)shown in FIG. 11 has the same configuration as that of the flowmeasurement processing step (Step S6 and Step S7) shown in FIG. 8, andaccordingly, the configuration is shown in brief in the drawing.

Thus, the doppler ultrasonic flowmeter 10B according to the presentembodiment, the flow measurement method using the doppler ultrasonicflowmeter 10B, and the flow measurement program employed for the dopplerultrasonic flowmeter 10B, have a function for making automatic selectionof an area where correct measurement has been made, and calculating theflow-speed distribution for the area thus selected, thereby enablingmore correct measurement of the flow-speed distribution regardless ofirregularities of the measurement results of the flow-speeddistribution. Furthermore, with the present embodiment, the flow thereofis computed based upon the correct measurement results of the flow-speeddistribution thus obtained, thereby enabling more correct flowmeasurement.

While description has been made regarding the doppler ultrasonicflowmeter 10B having a configuration wherein the flow-speed distributioncalculating member 67A includes the automatic area selecting element 75instead of the area selecting element 72, an arrangement may be madewherein the flow-speed distribution calculating member 67A includes boththe automatic area selecting element 75 and the area selecting element72. The doppler ultrasonic flowmeter having such a configuration allowsthe user to select a desired selection mode from the two kinds of theselection modes, i.e., the manual selection according to the selectionof the user, and the automatic selection. In this case, an arrangementmay be made wherein a menu is prepared for the user, wherein in theevent that the area has not been selected according to the selection ofthe user, the system makes automatic selection of the area for obtainingmore correct flow-speed distribution.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 10 shown in FIG. 1, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41B stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the flow measurement PG 41B, i.e.,a software component, has the functions serving as the dopplerultrasonic flowmeter 10B, the present embodiment may be applied to thedoppler ultrasonic flowmeter 50 or the doppler ultrasonic flowmeter 60.

Sixth Embodiment

FIG. 12 is a functional block diagram of a doppler ultrasonic flowmeter10C according to a sixth embodiment of the present invention.

The doppler ultrasonic flowmeter 10C shown in FIG. 12 has generally thesame configuration as that of the doppler ultrasonic flowmeter 10 shownin FIG. 1, wherein the computer 14 reads out and executes a flowmeasurement PG 41C stored in the storage member 37, whereby acombination of the Udflow unit 13, i.e., a hardware component unit, anda flow measurement PG 41C, i.e., a software component, has the functionsserving as the doppler ultrasonic flowmeter.

As shown in FIG. 12, the doppler ultrasonic flowmeter 10C includes theUdflow unit 13, the flow-speed distribution calculating member 67, theflow calculating member 68, and an optimum value calculating member 77for making automatic calculation of the optimum value which is used foradjustment of measurement, which depends upon the properties of theobject to be measured. Note that the doppler ultrasonic flowmeter 10Chas the same configuration wherein the Udflow unit 13 serving asflow-speed data acquisition member 18 and the flow-speed distributioncalculating member 67 form the flow-speed distribution measurement unit,and the Udflow unit 13, the flow-speed distribution calculating member67, and the flow calculating member 68, form the flow measurement unit.

The optimum value calculating member 77 includes: a data input element78 for receiving the information regarding the inner diameter Di of thefluid tube 11, the ultrasonic wave speed Cw in the fluid 12 to bemeasured, and the incident angle α of the ultrasonic pulses; a maximumflow-speed calculating element 79 for calculating the maximum flow speedV obtained based upon the flow-speed distribution measured by theflow-speed distribution calculating member 67; a normalized flow-speedcalculating element 80 for calculating the normalized flow-speed V₀which is obtained by dividing the calculated maximum flow-speed V by theultrasonic wave speed Cw in the fluid 12 to be measured; a normalizedfrequency calculating element 81 for calculating a normalized frequencyF₀ which is obtained by dividing the pulse repetition frequency f_(PRF)by the emission frequency f₀; and a frequency setting element 82 forresetting the emission frequency to an emission frequency f₁ whichsatisfies the following Expression.

[Expression 1]F ₀≧4V ₀·sin α, and f _(PRF) ≦Cw/2Di

The doppler ultrasonic flowmeter 10C has a configuration wherein thedata input element 78 of the optimum value calculating member 77receives the information regarding the inner diameter Di of the fluidtube 11, the ultrasonic wave speed Cw in the fluid 12 to be measured,and the incident angle α of the ultrasonic pulses, each of which areinitial values, and the maximum-flow-speed calculating element 79calculates the maximum flow speed V based upon the flow-speeddistribution measured by the flow-speed distribution calculating member67.

The normalized flow-speed calculating element 80 divides the maximumflow speed V calculated by the maximum-flow-speed calculating element79, by the ultrasonic wave speed Cw in the fluid 12 to be measured,regarding which the information has been received by the data inputelement 78, thereby calculating the normalized flow speed V₀. On theother hand, the normalized frequency calculating element 81 calculatesthe normalized frequency F₀ by dividing the pulse repetition frequencyf_(PRF) by the emission frequency f₀.

The frequency setting element 82 resets the emission frequency to theemission frequency f₁ so as to satisfy the relation represented by thefollowing Expression 1 including the normalized speed V₀ calculated bythe normalized speed calculating element 80 and the normalized frequencyF₀ calculated by the normalized frequency calculating element 81.F ₀≧4V ₀·sin α, and f _(PRF) ≦Cw/2Di

Note that the Expression 1 represents a range of the optimum values.Note that the relation represented by the Expression 1 has been proposedbased upon the experimental results obtained by the present inventor.

FIG. 13 through FIG. 15 are explanatory diagrams which show ranges ofthe optimum values, which have been proposed based upon the experimentalresults obtained by the present inventor.

FIG. 13 is an explanatory diagram which shows the region where theoptimum measurement can be made, and the region where the optimummeasurement cannot be made, wherein the horizontal axis represents thenormalized speed V*, and the vertical axis represents the normalizedfrequency F*. That is to say, it has been confirmed based upon theexperimental results, that optimum measurement can be made in the regionwhich satisfies the relation, F*≧4V₀·sin α, i.e., in the upperleftregion in the drawing.

FIG. 14 is an explanatory diagram which shows the region where theoptimum measurement can be made, and the region where the optimummeasurement cannot be made, wherein the horizontal axis represents thelogarithm of (Cw/Di), and the vertical axis represents the logarithm ofthe pulse repetition frequency f_(PRF). That is to say, it has beenconfirmed based upon the experimental results, that optimum measurementcan be made in the region which satisfies the relation, f_(PRF)≦Cw/2Di,i.e., in the lower-right region in the drawing.

FIG. 15 is an explanatory diagram which shows the region where theoptimum measurement can be made, and the region where the optimummeasurement cannot be made, with regard to typical tubes. An arrangementmay be made wherein the relation as shown in FIG. 15 is provided for theuser in the form which allows the user to obtain the relation on thenetwork, or in the form of a printed table. In this case, the user candetermine whether or not optimum measurement can be made under certainconditions, based upon the aforementioned information.

Now, description will be made step by step regarding the ultrasonic flowmeasurement procedure, i.e., measurement of the flow of the fluid 12 tobe measured, which is performed by the doppler ultrasonic flowmeter 10C.

FIG. 16 is an explanatory diagram for describing step by step regardingthe ultrasonic flow measurement procedure (which is denoted by “thirdultrasonic flow measurement procedure” in FIG. 16), i.e., the ultrasonicflow measurement method which is performed by the doppler ultrasonicflowmeter 10C.

As shown in FIG. 16, the ultrasonic flow measurement procedurecomprises: a reflector-group-speed calculating step (Step S21 and StepS22); a flow-speed distribution measurement processing step (Step S23and Step S24); an optimum-value setting step (Step S25) for calculatingthe optimum values of the basic frequency f₀, the pulse repetitionfrequency f_(PRF), and the incident angle α; and a flow measurementprocessing step (Step S26).

Specifically, the reflector-group-speed calculating step (Step S21 andStep S22) includes an initial-value acquisition step (Step S21), and areflector-group-speed calculating step (Step S22). First, the flowproceeds to Step S21, i.e., the initial-value acquisition step, whereinthe system receives the initial values of the basic frequency f₀ at thestart time of measurement, the pulse repetition frequency f_(PRF), andthe incident angle α. Then, the flow proceeds to Step S22, i.e., thereflector-group-speed calculating step, where the system casts theultrasonic pulses onto the fluid 12 to be measured, receives theultrasonic echoes so as to calculate the speed of each of the number ofreflectors 25 contained in the fluid 12 to be measured, and the Udflowunit 13 outputs the calculated flow-speed distribution of thereflector-groups 25 as the flow-speed distribution data. Then, thereflector-group-speed calculating step (Step S22) ends.

Upon completion of the reflector-group-speed calculating step, the flowproceeds to the flow-speed distribution measurement processing step(Step S23 and Step S24). First, the flow proceeds to the flow-speedcalculating distribution step (Step S23), where the flow-speeddistribution calculating member 67 calculates the flow-speeddistribution of the fluid 12 to be measured, and the center position.Subsequently, the flow proceeds to the flow-speed distribution dataoutput step (Step S24), where the flow-speed distribution calculatingmember 67 outputs the flow-speed distribution data and the centerposition, thus obtained. Upon output of the flow-speed distribution dataand the center position data from the flow-speed distributioncalculating member 67, the flow-speed distribution measurementprocessing step ends.

Upon completion of the flow-speed distribution measurement processingstep, the flow proceeds to the maximum-value setting step (Step S25),where the optimum-value calculating member 77 calculates the optimumvalues of the basic frequency f₀, the pulse repetition frequencyf_(PRF), and the incident angle α.

Specifically, the flow proceeds to the optimum-value setting step, i.e.,the emission frequency reset step for resetting the emission frequencyto the emission frequency f₁ which satisfies the following Expression.F ₀≧4V ₀·sin α, and f _(PRF) ≦Cw/2Di

Note that the optimum-value calculating member 77 resets the emissionfrequency f₁. Upon reset of the emission frequency f1 by theoptimum-value calculating member 77, the flow proceeds to the flow-speeddistribution measurement processing step, where the system calculatesthe flow-speed distribution using the updated emission frequency f1.Note that the flow-speed distribution measurement processing step andthe emission frequency reset step are repeated until the optimumemission frequency is obtained for measurement. Upon the systemobtaining the optimum emission frequency f1, the optimum-value settingstep (Step S25) ends.

Upon completion of the optimum-value setting step, the flow proceeds toStep S26, i.e., the flow measurement processing step. The flowmeasurement processing step, i.e., Step S26, has the same configurationas that of the flow measurement processing step (Step S6 and Step S7)shown in FIG. 8.

As described above, with the doppler ultrasonic flowmeter 10C accordingto the present embodiment, the flow measurement method using the dopplerultrasonic flowmeter 10C, and the flow measurement program employed forthe doppler ultrasonic flowmeter 10C, the optimum-value calculatingmember 77 has a function for automatic calculation of the optimum valueused for adjustment of measurement, which depends upon the properties ofthe object to be measured, thereby enabling measurement withoutpreliminary measurement for obtaining the optimum value used foradjustment of measurement, which depends upon the properties of theobject to be measured, and thereby reducing the load on the user due tothe troublesome procedure before measurement.

Note that an arrangement may be made wherein the data input element 78automatically receives the inner diameter Di of the fluid tube 11, theultrasonic wave speed Cw in the fluid 12 to be measured, and theincident angle α of the ultrasonic pulses, or an arrangement may be madewherein the user manually inputs the aforementioned information to thedata input element 78.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 10 shown in FIG. 1, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41C stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the flow measurement PG 41C, i.e.,a software component, has the functions serving as the dopplerultrasonic flowmeter 10C, the present embodiment may be applied to thedoppler ultrasonic flowmeter 50 or the doppler ultrasonic flowmeter 60.

Seventh Embodiment

A doppler ultrasonic flowmeter 50A according to a seventh embodiment ofthe present invention has generally the same configuration as that ofthe doppler ultrasonic flowmeter 50 shown in FIG. 3, wherein thecomputer 14 reads out and executes a flow measurement PG 41D stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and a flow measurement PG 41D, i.e., asoftware component, has the functions serving as the doppler ultrasonicflowmeter 50A.

FIG. 17 is a functional block diagram of the doppler ultrasonicflowmeter 50A according to the seventh embodiment of the presentinvention.

The doppler ultrasonic flowmeter 50A comprises: a Udflow unit 13including the incident angle adjusting/setting member 51; the flow-speeddistribution calculating member 67; the flow calculating member 68; anoptimum-value calculating member 77A for making automatic selection ofthe optimum value used for adjustment of measurement, which depends uponthe properties of the object to be measured. Note that the dopplerultrasonic flowmeter 50A according to the present embodiment has thesame configuration wherein the Udfow unit 13 serving as the flow-speeddata acquisition member 18 and the flow-speed distribution calculatingmember 67 form the flow-speed distribution measurement unit, and theUdflow unit 13, the flow-speed distribution calculating member 67, andthe flow calculating member 68, form the flow measurement unit.

The optimum-value calculating member 77A comprises: the data inputelement 78; the maximum-flow-speed calculating element 79; thenormalized speed calculating element 80; the normalized frequencycalculating element 81; an incident angle setting element 84 forresetting the incident angle to α1, which satisfies the followingExpression.F ₀≧4V ₀·sin α, and f _(PRF) ≦Cw/2Di

With the doppler ultrasonic flowmeter 50A, the data input element 78 ofthe optimum-value calculating member 77 receives the initial values ofthe inner diameter Di of the fluid tube 11, the ultrasonic wave speed Cwin the fluid 12 to be measured, and the incident angle α of theultrasonic pulses. Furthermore, the maximum flow-speed calculatingelement 79 thereof calculates the maximum flow speed V based upon theflow-speed distribution measured by the flow-speed distributioncalculating member 67.

The normalized speed calculating element 80 calculates the normalizedflow speed V₀ which is obtained by dividing the maximum flow speed Vcalculated by the maximum flow-speed calculating element 79, by theultrasonic wave speed Cw in the fluid 12 to be measured; Cw having beenreceived by the data input element 78. On the other hand, the normalizedfrequency calculating element 81 calculates the normalized frequency F₀which is obtained by dividing the pulse repetition frequency f_(PRF) bythe emission frequency f₀.

The incident angle setting element 84 resets the incident angle to α1which satisfies the relation represented by the following Expression 1including the normalized flow speed V₀ calculated by the normalizedspeed calculating element 80 and the normalized frequency F₀ calculatedby the normalized frequency calculating element 81.F ₀≧4V ₀·sin α, and f _(PRF) ≦Cw/2Di

Note that the relation represented by the Expression 1 represents therange of the optimum values shown in FIG. 13 through FIG. 15, and hasbeen proposed based upon the experimental results obtained by thepresent inventor.

FIG. 18 is an explanatory diagram for making description step by stepregarding the ultrasonic flow measurement procedure (which is denoted by“fourth ultrasonic flow measurement procedure” in FIG. 18), i.e., theultrasonic flow measurement method employed for the doppler ultrasonicflowmeter 50A.

As shown in FIG. 18, the ultrasonic flow measurement procedurecomprises: a reflector-group-speed calculating step (Step S31 and StepS32); a flow-speed distribution measurement processing step (Step S33and S34); an optimum-value setting step for calculating the optimumvalues of the basic frequency f₀, the pulse repetition frequencyf_(PRF), and the incident angle α (Step S35); and a flow measurementprocessing step (Step S36).

The reflector-group-speed calculating step (Step S31 and Step S32)comprises an initial-value acquisition step (Step S31) and thereflector-group-speed calculating step (step S32). First, the flowproceeds to Step S31, i.e., the initial-value acquisition step, wherethe system receives the initial values of the basic frequency f₀ at thestart time of measurement, the pulse repetition frequency f_(PRF), andthe incident angle α. Then, the flow proceeds to Step S32, i.e., thereflector-group-speed calculating step, the system calculates the speedof each of the number of reflectors 25 contained in the fluid 12 to bemeasured, and the Udflow unit 13 outputs the calculated flow-speeddistribution of the reflectors 25 as the flow-speed distribution data.

Next, the flow proceeds to the flow-speed distribution calculating step(Step S33) in the flow-speed distribution measurement processing step(step S33 and Step S34), where the flow-speed distribution calculatingmember 67 calculates the flow-speed distribution of the fluid 12 to bemeasured and the center position. Subsequently, the flow proceeds to theflow-speed distribution data output step (Step S34), where theflow-speed distribution calculating member 67 outputs the flow-speeddistribution data and the center position data thus calculated. Uponoutput of the flow-speed distribution data and the center position data,the flow-speed distribution measurement processing step ends.

Upon completion of the flow-speed distribution measurement processingstep, the flow proceeds to the optimum-value setting step (Step S35),where the optimum-value calculating member 77A calculates the optimumvalues of the basic frequency f₀, the pulse repetition frequencyf_(PRF), and the incident angle α.

Specifically, in the optimum-value setting step, i.e., theincident-angle reset step, in this case, the system resets the incidentangle to α1 which satisfies the following Expression.F ₀≧4V ₀·sin α, and f _(PRF) ≦Cw/2Di

Note that the optimum-value calculating member 77A resets the incidentangle to α1. Upon reset of the incident angle to the optimum incidentangle α1 for measurement, the optimum-value setting step (Step S35)ends.

Upon completion of the optimum-value setting step, the flow proceeds toStep S26, i.e., the flow measurement processing step. The flowmeasurement processing step has the same configuration as that of theflow measurement processing step (Step S6 and Step S7) shown in FIG. 8.

As described above, with the doppler ultrasonic flowmeter 50A accordingto the present embodiment, the flow measurement method using the dopplerultrasonic flowmeter 50A, and the flow measurement program employed forthe doppler ultrasonic flowmeter 50A, the optimum-value calculatingmember 77A has a function for automatic calculation of the optimum valueused for adjustment of measurement, which depends upon the properties ofthe object to be measured, thereby enabling measurement withoutpreliminary measurement for obtaining the optimum value used foradjustment of measurement, which depends upon the properties of theobject to be measured, and thereby reducing the load placed on the userby the troublesome procedure before measurement.

Note that an arrangement may be made wherein the data input element 78automatically receives the inner diameter Di of the fluid tube 11, theultrasonic wave speed Cw in the fluid 12 to be measured, and theincident angle α of the ultrasonic pulses, or an arrangement may be madewherein the user manually inputs the aforementioned information to thedata input element 78.

While description has been made regarding an arrangement wherein theoptimum-value calculating member 77A comprises the data input element78, the maximum flow-speed calculating element 79, the normalized speedcalculating element 80, the normalized frequency calculating element 81,and the incident angle setting element 84, an arrangement may be madewherein the optimum-value calculating member 77A further comprises thefrequency setting element 82 in the same way as with the optimum-valuecalculating member 77.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 50 shown in FIG. 3, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41D stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the flow measurement PG 41D, i.e.,a software component, has the functions serving as the dopplerultrasonic flowmeter 50A, the present embodiment may be applied to thedoppler ultrasonic flowmeter 60.

Eight Embodiment

FIG. 19 is a functional block diagram of a doppler ultrasonic flowmeter10D according to an eighth embodiment of the present invention.

The doppler ultrasonic flowmeter 10D shown in FIG. 19 has generally thesame configuration as that of the doppler ultrasonic flowmeter 10 shownin FIG. 1, wherein the computer 14 reads out and executes a flowmeasurement PG 41E stored in the storage member 37, whereby acombination of the Udflow unit 13, i.e., a hardware component unit, anda PG 41E, i.e., a software component, has the functions serving as thedoppler ultrasonic flowmeter.

As shown in FIG. 19, the doppler ultrasonic flowmeter 10D includes: theUdflow unit 13; the flow-speed distribution calculating member 67; theflow calculating member 68; a channel distance computing member 87 forcomputing the minimum channel distance based upon the frequency and thespeed of the ultrasonic pulses; a measurement range display member 88for computing and displaying the measurement range based upon theminimum channel distance thus computed; and channel distancechange/setting member 89 which allows the user to determine whether ornot the minimum channel distance is changed to the value obtained bymultiplying the initial minimum channel distance by an integer.

The channel distance computing member 87 computes the minimum channeldistance based upon the frequency and the speed of the ultrasonicpulses. The measurement range display member 88 computes the measurementrange based upon the minimum channel distance computed by the channeldistance computing member 87, and displays the computation results ondisplay. The channel distance change/setting member 89 receives arequest for change and setting of the minimum channel distance, whichallows the user to determine whether or not the minimum channel distanceis changed to the value obtained by multiplying the initial minimumchannel distance by an integer.

Let us say that the ultrasonic pulse is cast from the transducer ontothe fluid, is reflected from the far-side tube wall, and received by thereflected-wave receiver, just during the pulse repetition cycle(=1/f_(PRF)). In this case, the maximum value of the channel distancewhich can be set by the channel distance change/setting member 89matches the tube diameter of the fluid tube 11. Accordingly, the maximumvalue of the channel distance can be varied by adjusting the pulserepetition frequency f_(PRF). Note that it can be understood that thesystem can set the maximum channel distance sufficient for measurementof the actual fluid tube 11 having the largest tube diameter, based uponthe fact that the system can set a desired pulse repetition frequencyf_(PRF) from the minimum in order of 1 Hz, and the ultrasonic wave speedCw is in order of 1000 m/s in the fluid 12 to be measured.

FIG. 20 is an explanatory diagram for making description step by stepregarding the ultrasonic flow measurement procedure (which is denoted by“fifth ultrasonic flow measurement procedure” in FIG. 20), i.e., theultrasonic flow measurement method employed for the doppler ultrasonicflowmeter 10D.

As shown in FIG. 20, the ultrasonic flow measurement procedure performedby the doppler ultrasonic flowmeter 10D comprises: areflector-group-speed calculating step (Step S41); a flow-speeddistribution measurement processing step (Step S42); a channel distancecomputing step (step S43); a measurement range display step (Step S44through Step S46); a channel distance changing step (Step S47); and aflow measurement processing step (Step S48).

The reflector-group-speed calculating step (Step S41) has the sameconfiguration as that of the reflector-group-speed calculating step(Step S1) shown in FIG. 8, wherein the Udflow unit 13 calculates thespeed of each of the number of reflectors 25 contained in the fluid 12to be measured, and the Udflow unit 13 outputs the calculated flow-speeddistribution of the reflectors 25 as the flow-speed distribution data.Furthermore, the Udflow unit 13 outputs the data of the frequency f₀ ofthe ultrasonic pulses and the ultrasonic wave speed Cw required forcomputation in the channel distance computation step (Step S43). Uponcompletion of the reflector-group-speed calculating step, the flowproceeds to the flow-speed distribution measurement processing step(Step S42).

In Step S42, i.e., the flow-speed distribution measurement processingstep, the flow-speed distribution calculating member 67 calculates theflow-speed distribution data of the fluid 12 to be measured and thecenter position data of the fluid tube 11 based upon the flow-speeddistribution data of the reflectors 25. Upon calculation of theflow-speed distribution data of the fluid 12 to be measured, and thecenter position data of the fluid tube 11, the flow-speed distributionmeasurement processing step (Step S42) ends, following which the flowproceeds to the channel distance computing step (Step S43).

In Step S43, i.e., the channel distance computing step, the channeldistance computing member 87 computes the minimum channel distance basedupon the frequency f₀ of the ultrasonic pulses at the time ofmeasurement and the ultrasonic wave speed Cw. Upon computation of theminimum channel distance, the channel distance computing step ends,following which the flow proceeds to the measurement range display steps(Step S44 through Step S46).

The measurement range display steps (Step S44 through Step S46)comprises: a measurement range computing step (Step S44) for computingthe measurement range based upon the minimum channel distance computedby the channel distance computing member 87; a measurement range displaystep (Step S45) for displaying the data of the measurement rangecomputed in the measurement range computing step on display; and achannel distance change/setting determination step (Step S46) whichallows the user to determine whether or not the channel distance ischanged, through the display.

In the measurement range display steps (Step S44 through Step S46),first, the flow proceeds to Step S44, i.e., the measurement rangecomputing step, where the measurement range display member 88 computesthe measurement range, following which the flow proceeds to Step S45,i.e., the measurement range display step, where the measurement rangedisplay member 88 outputs the data of the measurement range, and thecomputation processing member 35 of the computer 14 displays theinformation regarding the measurement range outputs from the measurementrange display member 88 on the display monitor 39.

FIG. 21 is a schematic explanatory diagram which shows an example of ascreen displayed on the display monitor 39 as a result of themeasurement range display step (Step S45).

As shown in FIG. 21, a measurement range bar 91 is displayed on theupper portion of the flow-speed distribution display portion 92, whichallows the user to confirm the measurement range.

Note that while the arrangement shown in FIG. 21 has a simple layout forconvenience of description, it is needless to say that the layout of thescreen may further include the information regarding the frequency ofthe ultrasonic pulses, the ultrasonic wave speed, and so forth, asnecessary.

Furthermore, at the same time of display of the measurement range bar 91on the display monitor 39, the flow proceeds to Step S46, i.e., thechannel distance change/setting determination step, where the systemdisplays a dialog box (which will be referred to as “channel distancechange/setting determination dialog box” hereafter) 93 on the displaymonitor 39, which allows the user to determine whether or not thechannel distance is changed. Upon display of the measurement range barand the channel distance change/setting determination dialog box, themeasurement range display steps (Step S44 through Step S46) ends.

In the event that the user has determined that there is no need tochange the minimum channel distance in particular through the minimumchannel distance change/setting determination dialog box displayed onthe display monitor 39 in Step S46, i.e., the channel distancechange/setting determination step (in a case of “NO” in Step S46), theflow proceeds to the flow measurement processing step (Step S48). Theflow measurement processing step (Step S48) has the same configurationas that of the flow measurement processing step (Step S6 and Step S7)shown in FIG. 8. Upon completion of the Step S48, i.e., the flowmeasurement processing step, the ultrasonic flow measurement procedureends.

On the other hand, in the event that the user has determined that thereis the need to change the minimum channel distance through the minimumchannel distance change/setting determination dialog box 93 displayed onthe display monitor 39 in Step S46, i.e., the channel distancechange/setting determination step (in a case of “YES” in Step S46), theflow proceeds to the channel distance changing step (Step S47).

In the channel distance changing step, the channel distancechange/setting member 89 changes the channel distance by multiplying theminimum channel distance by an integer corresponding to the requestinput by the user. In a case of input of a request that measurement ismade with the channel distance twice the minimum distance channel, thechannel distance is set to twice the minimum channel distance.

As shown in FIG. 21, the system provides a GUI, e.g., a channel distancesetting window 94 displayed on the display monitor 39, which allows theuser to change the channel distance through the input member 38 of thepersonal computer 14. Alternatively, the user selects and operates(click operation) a vertical cursor 95 displayed on the side of thechannel distance setting window 94 through the input member 38 of thepersonal computer 14 so as to adjust the channel distance in incrementsof the minimum channel distance. Note that in a case wherein the usersets the value in the channel distance setting window 94 to 2, thechannel distance is set to twice the minimum channel distance.

Upon completion of setting processing by the channel distancechange/setting member 89 wherein the channel distance is set to thevalue obtained by multiplying the minimum channel distance by an integerwhich has been input in the channel distance setting window 94, thechannel distance changing step (Step S47) ends, following which the flowproceeds to Step S42. Then, the system executes the processing stepsfollowing Step S42.

Next, description will be made regarding the estimation results of therelation between the measurement precision of the doppler ultrasonicflowmeter 10D and the channel distance which is obtained by multiplyingthe minimum channel distance by an integer, based upon the measurementresults.

(Estimation Results of the Relation Between the Measurement Precisionand the Channel Distance)

The first measurement was made as follows. That is to say, flowmeasurement was made with regard to water flowing within the fluid tube11 with an inner diameter of 150 mm, serving as the fluid 12 to bemeasured, with a sampling frequency of 1 MHz, and with a channeldistance of twice the minimum channel distance.

In a case of measurement of water serving as the fluid 12 to bemeasured, with an sampling frequency of 1 MHz, the minimum channeldistance is approximately 0.75 mm, based upon the fact that theultrasonic wave speed is 1480 m/s in water. On the other hand, thedoppler ultrasonic flowmeter 10D used for the present measurementincludes 128 channels, and accordingly, the measurement depth (distance)becomes 128×0.75 mm=96 mm. Accordingly, it can be understood that thechannel distance needs to be set to at least twice or more the minimumchannel distance.

In the first measurement using the doppler ultrasonic flowmeter 10D, theflow-speed distribution was obtained with 100 channels (=150 mm/1.5 mm)of the 128 channels included in the doppler ultrasonic flowmeter 10D.

Next, the second measurement was made as follows. That is to say, flowmeasurement was made with regard to water flowing within the fluid tube11 with an inner diameter of 150 mm, serving as the fluid 12 to bemeasured, with a sampling frequency of 1 MHz, and with a channeldistance of three times the minimum channel distance.

With the second measurement, the channel distance becomes three timesthe minimum channel distance, i.e., 0.75 mm×3=2.25 mm, and accordingly,the measurement depth (distance) becomes 128×2.25 mm=288 mm. On theother hand, in the second measurement, the flow-speed distribution wasobtained with 67 channels (=150 mm/2.25 mm) of the 128 channels includedin the doppler ultrasonic flowmeter 10D.

Next, the third measurement was made with a reduced number of themeasurement channels. As a result of the third measurement, it has beenconfirmed that high measurement can be made with a sufficiently smallererror than 1% from the true value, even if measurement is made withapproximately half the measurement channels.

As can be understood from the measurement results described above, ithas been confirmed that the doppler ultrasonic flowmeter according tothe present embodiment exhibits high measurement performance without aparticular countermeasure for handling measurement with a large-diameterfluid tube, or improving measurement precision, such as a configurationincluding the 256 channels or 512 channels; the number being greaterthan with the present embodiment including the 128 channels.

Specifically, it has been confirmed that with a doppler ultrasonicflowmeter having a configuration wherein the flow-speed distribution iscalculated based upon the ultrasonic echoes received by the measurementchannels of which the maximum number is 128, high-precision measurementcan be made with a sufficiently smaller error than 1% for any tube in alarge diameter range from a large inner diameter exceeding 280 mm, to asmall inner diameter less than 100 mm (e.g., in a case of employing thechannel distance three times the minimum channel distance, measurementwas made with an error of 0.0056%).

As described above, with the doppler ultrasonic flowmeter 10D accordingto the present embodiment, the flow measurement method using the dopplerultrasonic flowmeter 10D, and the flow measurement program employed forthe doppler ultrasonic flowmeter 10D, the user can determine to changethe measurement range based upon the relation between the measurementrange calculated based upon the minimum channel distance and the tubediameter of the fluid tube within which the fluid to be measured flows,as necessary, and the flow-speed distribution is computed based upon themeasurement results with the changed measurement range, thereby enablingextension of the measurement range.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 10 shown in FIG. 1, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41E stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the PG 41E, i.e., a softwarecomponent, has the functions serving as the doppler ultrasonic flowmeter10D, the present embodiment may be applied to the doppler ultrasonicflowmeter 50 or the doppler ultrasonic flowmeter 60.

While description has been made regarding the doppler ultrasonicflowmeter 10D having a configuration wherein the mechanism which allowsthe system to adjust the measurement range by setting the channeldistance to a value obtained by multiplying the minimum channel distanceby an integer is applied to a doppler ultrasonic flowmeter including 128measurement channels, the present invention is not restricted to theaforementioned arrangement, rather, arrangements may be made wherein theaforementioned mechanism is applied to a doppler ultrasonic flowmeterincluding 128 or more measurement channels.

Ninth Embodiment

FIG. 22 is a functional block diagram of a doppler ultrasonic flowmeter10E according to a ninth embodiment of the present invention.

The doppler ultrasonic flowmeter 10E shown in FIG. 22 has generally thesame configuration as that of the doppler ultrasonic flowmeter 10 shownin FIG. 1, wherein the computer 14 reads out and executes a flowmeasurement PG 41F stored in the storage member 37, whereby acombination of the Udflow unit 13, i.e., a hardware component unit, anda flow measurement PG 41F, i.e., a software component, has the functionsserving as the doppler ultrasonic flowmeter.

As shown in FIG. 22, the doppler ultrasonic flowmeter 10E has the sameconfiguration as that of the doppler ultrasonic flowmeter 10D shown inFIG. 19, except for a configuration including a channel distanceautomatic change/determination member 97, instead of the channeldistance change/setting member 89. Accordingly, the same components aredenoted by the same reference numerals, and description thereof will beomitted. Note that the present embodiment has the same configurationwherein the Udflow unit 13 serving as the flow-speed data acquisitionmember 18 and the flow-speed distribution calculating member 67 form theflow-speed distribution measurement unit, and the Udflow unit 13, theflow-speed distribution calculating member 67, and the flow calculatingmember 68, form the flow measurement unit.

The doppler ultrasonic flowmeter 10E includes: the Udflow unit 13; theflow-speed distribution calculating member 67; the flow calculatingmember 68; the channel distance computing member 87; the measurementrange display member 88; and the cannel distance automaticchange/determination member 97 for automatically determining whether ornot the channel distance is set to a value obtained by multiplying theminimum channel distance by an integer. Specifically, the channeldistance automatic change/determination member 97 automaticallydetermines whether or not the channel distance is set to a valueobtained by multiplying the minimum channel distance by an integer,based upon the minimum channel distance, the tube diameter of the fluidtube 11, and the maximum number of the measurement channels.

FIG. 23 is an explanatory diagram for making description step by stepregarding the ultrasonic flow measurement procedure (which is denoted by“sixth ultrasonic flow measurement procedure” in FIG. 23), i.e., theultrasonic flow measurement method employed for the doppler ultrasonicflowmeter 10E.

As shown in FIG. 23, the ultrasonic flow measurement procedure performedby the doppler ultrasonic flowmeter 11E comprises: areflector-group-speed calculating step (Step S51); a flow-speeddistribution measurement processing step (Step S52); a channel distancecomputing step (step S53); a measurement range display step (Step S54and Step S55); a flow-speed distribution information display step (StepS56); a flow measurement processing step (Step S57); and a channeldistance changing step (Step S58).

The reflector-group-speed calculating step (Step S51) has the sameconfiguration as that of the reflector-group-speed calculating step(Step S41) shown in FIG. 20, wherein the Udflow unit 13 calculates thespeed of each of the number of reflectors 25 contained in the fluid 12to be measured, and the Udflow unit 13 outputs the calculated flow-speeddistribution of the reflectors 25, and the data of the frequency f₀ ofthe ultrasonic pulses and the ultrasonic wave speed Cw. Upon completionof the reflector-group-speed calculating step, the flow proceeds to theflow-speed distribution measurement processing step (Step S52).

In Step S52, i.e., the flow-speed distribution measurement processingstep, the flow-speed distribution calculating member 67 calculates theflow-speed distribution data of the fluid 12 to be measured and thecenter position data of the fluid tube 11 based upon the flow-speeddistribution data of the reflectors 25. Upon calculation of theflow-speed distribution data of the fluid 12 to be measured, and thecenter position data of the fluid tube 11, the flow-speed distributionmeasurement processing step (Step S52) ends, following which the flowproceeds to the channel distance computing step (Step S53).

In Step S53, i.e., the channel distance computing step, the channeldistance computing member 87 computes the minimum channel distance basedupon the frequency f₀ of the ultrasonic pulses at the time ofmeasurement and the ultrasonic wave speed Cw. Upon computation of theminimum channel distance, the channel distance computing step ends,following which the flow proceeds to the measurement range calculatingstep (Step S54 and Step S55).

The measurement range calculating step (Step S54 and Step S55)comprises: a measurement range computing step (Step S54) for computingthe measurement range based upon the minimum channel distance computedby the channel distance computing member 87; and a channel distancechange determination step (Step S55) for determining whether or not thechannel distance needs to be changed.

In the measurement range calculating step (Step S54 and Step S55),first, the flow proceeds to Step S54, i.e., the measurement rangecomputing step, where the measurement range display member 88 computesthe measurement range, following which the flow proceeds to Step S55,i.e., the channel distance change determination step, where the canneldistance automatic change/determination member 97 determines whether ornot the channel distance needs to be changed based upon the measurementrange calculated by the measurement range display member 88 and the tubediameter of the fluid tube within which the fluid to be measured flows.

In the event that the channel distance automatic change/determinationmember 97 has determined that the channel distance needs not to bechanged in the channel distance change determination step (in a case of“NO” in Step S55), the flow proceeds to the flow-speed distributioninformation display step (step S56), where the system displays theinformation regarding the flow-speed distribution of the fluid 12 to bemeasured, and the measurement range, on the display monitor 39.

Upon display of information regarding the flow-speed distribution of thefluid 12 to be measured, and the measurement range, on the displaymonitor 39, the flow-speed distribution information display step (stepS56) ends, following which the flow proceeds to the flow measurementprocessing step (Step S57). The flow measurement processing step (StepS57) has the same configuration as that of the flow measurementprocessing step (Step S6 and Step S7) shown in FIG. 8. Then, uponcompletion of Step S57, i.e., the flow measurement processing step, theultrasonic flow measurement procedure ends.

On the other hand, in the event that the channel distance automaticchange/determination member 97 has determined that the channel distanceneeds to be changed in the channel distance change determination step(in a case of “YES” in Step S55), the flow proceeds to the channeldistance changing step (Step S58).

The channel distance changing step (Step S58) has the same configurationas that of the channel distance changing step (Step S47) shown in FIG.20, where the channel distance automatic change/determination member 97sets the channel distance to a value which is obtained by multiplyingthe minimum channel distance by an integer. Upon completion of thechannel distance changing step, the flow returns to Step S52, and thesystem performs processing steps following Step S52.

As described above, with the doppler ultrasonic flowmeter 10E accordingto the present embodiment, the flow measurement method using the dopplerultrasonic flowmeter 10E, and the flow measurement program employed forthe doppler ultrasonic flowmeter 10E, the channel distance automaticchange/determination member 97 determines whether or not the channeldistance needs to be changed based upon the measurement range calculatedfrom the minimum channel distance and the tube diameter of the fluidtube within which the fluid to be measured flows, and automaticallychange the measurement range, as necessary, for measurement of theflow-speed distribution.

This enables extension of the measurement range in the same way as withthe doppler ultrasonic flowmeter 10D according to the presentembodiment, the flow measurement method using the doppler ultrasonicflowmeter 10D, and the flow measurement program employed for the dopplerultrasonic flowmeter 10D. Furthermore, an arrangement with an extendedmeasurement range exhibits a high-precision measurement performance witha sufficiently smaller error than 1%.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 10 shown in FIG. 1, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41F stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the flow measurement PG 41F, i.e.,a software component, has the functions serving as the dopplerultrasonic flowmeter 10E, the present embodiment may be applied to thedoppler ultrasonic flowmeter 50 or the doppler ultrasonic flowmeter 60.

While description has been made regarding the doppler ultrasonicflowmeter 10E including the channel distance automaticchange/determination member 97, instead of the channel distancechange/setting member 89, the doppler ultrasonic flowmeter 10E mayinclude both the channel distance automatic change/determination member97 and the channel distance change/setting member 89. The dopplerultrasonic flowmeter having such a configuration allows the user toselect a desired selection mode from the two kinds of the selectionmodes, i.e., the manual selection according to the selection of theuser, and the automatic selection. In this case, an arrangement may bemade wherein a menu is prepared for the user, wherein in the event thatthe channel distance has not been changed according to the selection ofthe user, the system automatically changes the channel distance to amore suitable value for measurement.

Tenth Embodiment

FIG. 24 is a functional block diagram of a doppler ultrasonic flowmeter10F according to a tenth embodiment of the present invention.

The doppler ultrasonic flowmeter 10F shown in FIG. 24 has generally thesame configuration as that of the doppler ultrasonic flowmeter 10 shownin FIG. 1, wherein the computer 14 reads out and executes a flowmeasurement PG 41G stored in the storage member 37, whereby acombination of the Udflow unit 13, i.e., a hardware component unit, anda flow measurement PG 41G, i.e., a software component, has the functionsserving as the doppler ultrasonic flowmeter.

As shown in FIG. 24, the doppler ultrasonic flowmeter 10F includes: theUdflow unit 13; the flow-speed distribution calculating member 67; theflow calculating member 68; a flow-speed distribution output member 99for outputting the relation between the flow-speed distribution of thefluid 12 to be measured and the distance in the direction of themeasurement line ML in the form of an image; a flow-speed zero-pointdisplay member 100 for displaying the zero points which represents theflow speed of zero in the form of a continuous line; and a flow-speedmeasurement range switching member 101 for switching the measurementrange (which will be referred to as “flow-speed measurement range”hereafter) of the flow-speed distribution measurement unit between anormal range mode and a double-range mode where the system displays theflow-speed distribution in a positive measurement range alone with aflow-speed measurement range twice that of the normal mode.

Note that the present embodiment has the same configuration wherein theUdflow unit 13 serving as the flow-speed data acquisition member 18 andthe flow-speed distribution calculating member 67 form the flow-speeddistribution measurement unit, and the Udflow unit 13, the flow-speeddistribution calculating member 67, and the flow calculating member 68,form the flow measurement unit.

The flow-speed distribution output member 99 displays the relationbetween the flow-speed distribution data of the fluid 12 to be measured,which has been output from the flow-speed distribution calculatingmember 67, and the distance in the direction of the measurement line ML,on the display monitor 39. The flow-speed zero-point display member 100superimposes a flow-speed zero line which represents the flow speed ofzero, on the flow-speed distribution displayed on the display monitor39.

The flow-speed measurement range switching member 101 allows the user toswitch the measurement mode between the normal range mode and thedouble-range mode where the flow-speed distribution or the flow is notmeasured in the negative range, but is measured in the positivemeasurement range alone. This allows the system to make measurementwithout handling the information whether the measurement results belongto the positive measurement range or the negative range, andaccordingly, the performance which has been used for handling suchinformation become available, thereby increasing the performance formeasurement of the flow speed, and thereby increasing the flow-speedmeasurement range to twice that of the normal range mode, at the time offlow measurement in the positive measurement range alone.

FIG. 25 shows examples of graphic images displayed on the displaymonitor 39 by the flow-speed distribution output member 99 of thedoppler ultrasonic flowmeter 10E, which show the relations between theflow-speed distribution data of the fluid 12 to be measured, which hasbeen output from the flow-speed distribution calculating member 67, andthe distance in the direction of the measurement line ML.

Note that FIG. 25(A) shows the state where the flow-speed measurementrange switching member 101 has not switched the measurement mode to thedouble-range mode for measuring the flow speed in the positivemeasurement range alone, i.e., the state in the normal range mode. Onthe other hand, FIG. 25(B) shows the state where the flow-speedmeasurement range switching member 101 has switched the measurement modeto the double-range mode for measuring the flow speed in the positivemeasurement range alone.

In FIG. 25(A), the flow-speed distribution concentrates on the upperportion (in the positive range of the flow speed) as to the flow-speedzero line 103, and a part of the points which represents the flow-speeddistribution at the corresponding position of the tube 11 exhibitsgreater flow speed than the maximum flow speed which can be measured atthe normal range mode. In this case, upon the user selecting (clicking)the a “positive” radio button of a flow-speed range switching GUI 104 soas to switch a “normal” radio button to the “positive” radio button, theflow-speed measurement range switching member 101 switches themeasurement range to the double-measurement-range.

Upon switching of the flow-speed-measurement range to thedouble-measurement-range, the flow-speed zero line 103 matches thehorizontal axis, and the flow-speed distribution is not displayed in thenegative range, but is displayed in the positive range with a flow-speedmeasurement range twice that of the normal measurement range, as shownin FIG. 25(B). Note that FIG. 25(B) shows an example wherein theflow-speed distribution is displayed over all the positions of the tube11 as a result of switching of the flow-speed measurement range to thedouble-measurement-range.

FIG. 26 is an explanatory diagram for making description step by stepregarding the ultrasonic flow measurement procedure (which is denoted by“seventh ultrasonic flow measurement procedure” in FIG. 26), i.e., theultrasonic flow measurement method employed for the doppler ultrasonicflowmeter 10F.

As shown in FIG. 26, the ultrasonic flow measurement procedure performedby the doppler ultrasonic flowmeter 10F comprises: areflector-group-speed calculating step (Step S61); a flow-speeddistribution measurement processing step (Step S62); a flow-speeddistribution output step (Step S63) for outputting the relation betweenthe flow-speed distribution of the fluid 12 to be measured and thedistance in the direction of the measurement line ML in the form of animage on a screen; a flow-speed zero-line display step (Step S64) forsuperimposing the flow-speed zero line 103 on the flow-speeddistribution displayed on the screen in the flow-speed distributionoutput step; a flow-speed measurement range switching determination step(Step S65) which allows the user to determine whether or not theflow-speed measurement range is switched; a flow measurement processingstep (Step S66); and a flow-speed measurement range switching step (StepS67) for switching the measurement mode between the normal range modeand the double-range mode which allows the measurement of the positiveflow speed with a flow-speed measurement range twice that of the normalrange.

The reflector-group-speed calculating step (Step S61) has the sameconfiguration as that of the reflector-group-speed calculating step(Step S1) shown in FIG. 8. Upon completion of the reflector-group-speedcalculating step (Step S61), the flow proceeds to the flow-speeddistribution measurement processing step (Step S62).

In the flow-speed distribution measurement processing step (step S62),the system performs the same processing as in the flow-speeddistribution measurement processing step (step S2). Upon completion ofthe flow-speed distribution measurement processing step (Step S62), theflow proceeds to the flow-speed distribution output step (Step S63),where the flow-speed distribution output member 99 outputs the relationbetween the flow-speed distribution of the fluid 12 to be measured andthe distance in the direction of the measurement line ML in the form ofan image on the display monitor 39 as shown in FIG. 25.

Upon completion of the flow-speed distribution output step, the flowproceeds to the flow-speed zero-line display step (Step S64), where theflow-speed zero-point display member 100 superimposes the flow-speedzero line 103 on the flow-speed distribution displayed on the screen inthe flow-speed distribution output step. Upon completion of theflow-speed zero-line display step (Step S64), the flow proceeds to theflow-speed measurement range switching determination step (Step S65),where the flow-speed measurement range switching member 101 displays aGUI on the display monitor 39, which allows the user to determinewhether or not the flow-speed measurement range switching member 101switches the flow-speed range.

The user determines whether or not the flow-speed measurement rangeswitching member 101 switches the flow-speed range, through the GUIdisplayed on the display monitor 39 by operating the input member 38 ofthe computer 14. In the event that the user has given instructions tothe flow-speed measurement range switching member 101 that theflow-speed range is not switched, through the input member 38 (in a caseof “NO” in Step S65), the flow proceeds to the flow measurementprocessing step (Step S66). The flow measurement processing step (StepS66) has the same configuration as that of the flow measurementprocessing step (Step S6 and Step S7) shown in FIG. 8. Upon completionof Step S66, i.e., the flow measurement processing step, the ultrasonicflow measurement procedure ends.

On the other hand, in the event that the user has given instructions tothe flow-speed measurement range switching member 101 that theflow-speed range is switched, through the input member 38 (in a case of“YES” in Step S65), the flow proceeds to the flow-speed measurementrange switching step (Step S67). In the flow-speed measurement rangeswitching step (Step S67), the flow-speed measurement range switchingmember 101 switches the flow-speed measurement range between the normalmeasurement range and the double-measurement-range for measuring thepositive flow speed. Upon completion of the flow-speed measurement rangeswitching step, the flow proceeds to Step S65. Then, the system performsthe processing steps following Step S65.

As described above, the doppler ultrasonic flowmeter 10F according tothe present embodiment, the flow measurement method using the dopplerultrasonic flowmeter 10F, and the flow measurement program employed forthe doppler ultrasonic flowmeter 10F, allow the user to switch theflow-speed measurement range between the normal measurement range andthe double-measurement-range, thereby enabling flow measurement in anextended flow-speed measurement range twice that of the normalmeasurement range, as necessary.

While description has been made regarding an arrangement wherein thedoppler ultrasonic flowmeter 10F includes the flow-speed measurementrange switching member 101 having a function for switching theflow-speed measurement range between the normal measurement range andthe double-measurement-range, thereby enabling measurement of thepositive flow speed in an extended flow-speed measurement range twicethat of the normal measurement range, it is needless to say that anarrangement may be made wherein the doppler ultrasonic flowmeter 10F hasa function for switching the flow-speed measurement range between thenormal measurement range and the double-measurement-range, therebyenabling measurement of the negative flow speed in an extendedflow-speed measurement range twice that of the normal measurement range.In this case, the user should select a “negative” radio button of theflow-speed range switching GUI 104 shown in FIG. 25.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 10 shown in FIG. 1, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41G stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the flow measurement PG 41G, i.e.,a software component, has the functions serving as the dopplerultrasonic flowmeter 10F, the present embodiment may be applied to thedoppler ultrasonic flowmeter 50 or the doppler ultrasonic flowmeter 60.

Eleventh Embodiment

FIG. 27 is a functional block diagram of a doppler ultrasonic flowmeter10G according to an eleventh embodiment of the present invention.

The doppler ultrasonic flowmeter 10G shown in FIG. 27 has generally thesame configuration as that of the doppler ultrasonic flowmeter 10 shownin FIG. 1, wherein the computer 14 reads out and executes a flowmeasurement PG 41H stored in the storage member 37, whereby acombination of the Udflow unit 13, i.e., a hardware component unit, anda flow measurement PG 41H, i.e., a software component, has the functionsserving as the doppler ultrasonic flowmeter.

As shown in FIG. 27, the doppler ultrasonic flowmeter 10G has the sameconfiguration as that of the ultrasonic flowmeter 10F shown in FIG. 24,except for a configuration including a positive/negative determinationmember 106 for determining whether or not the calculated flow-speeddistribution of the fluid 12 to be measured contains any negative flowspeed components, and an automatic flow-speed range switching member 107for switching the flow-speed measurement range to thedouble-measurement-range mode which allows measurement of the positiveflow speed with a flow-speed measurement range twice that of the normalmeasurement range mode in the event that determination has been madethat the calculated flow-speed distribution contains no negative flowspeed components, instead of the flow-speed measurement range switchingmember 107.

Note that the present embodiment has the same configuration wherein theUdflow unit 13 serving as the flow-speed data acquisition member 18 andthe flow-speed distribution calculating member 67 form the flow-speeddistribution measurement unit, and the Udflow unit 13, the flow-speeddistribution calculating member 67, and the flow calculating member 68,form the flow measurement unit.

The positive/negative determination member 106 determines whether or notthe flow-speed distribution of the fluid 12 to be measured, which hasbeen calculated by the flow-speed distribution calculating member 67,contains any negative flow speed components. The automatic flow-speedrange switching member 107 switches the flow-speed measurement range totwice the measurement range of the normal measurement range mode, formeasuring the positive flow speed in the event that thepositive/negative determination member 106 has determined that thecalculated flow-speed distribution contains no negative flow speedcomponents, without instructions from the user whether or not theflow-speed measurement range is switched.

FIG. 28 is an explanatory diagram for making description step by stepregarding the ultrasonic flow measurement procedure (which is denoted by“eighth ultrasonic flow measurement procedure” in FIG. 28), i.e., theultrasonic flow measurement method employed for the doppler ultrasonicflowmeter 10G.

As shown in FIG. 28, the ultrasonic flow measurement procedure performedby the doppler ultrasonic flowmeter 10G comprises: areflector-group-speed calculating step (Step S71); a flow-speeddistribution measurement processing step (Step S72); a flow-speed rangeswitching determination step (Step S73 and Step S74) for determiningwhether or not the flow-speed measurement range is switched; aflow-speed distribution output step (Step S75); a flow-speed zero-linedisplay step (Step S76); a flow measurement processing step (Step S77);and a flow-speed measurement range switching step (Step S78).

With the ultrasonic flow measurement procedure performed by the dopplerultrasonic flowmeter 10G, first, the flow proceeds to thereflector-group-speed calculating step (Step S71), and the flow-speeddistribution measurement processing step (Step S72). Note that thereflector-group-speed calculating step (Step S71) and the flow-speeddistribution measurement processing step (Step S72) have the sameconfigurations as with the reflector-group-speed calculating step (StepS61) and the flow-speed distribution measurement processing step (StepS62) shown in FIG. 26, respectively.

Upon completion of the reflector-group-speed calculating step (Step S71)and the flow-speed distribution measurement processing step (Step S72),the flow proceeds to the flow-speed range switching determination step(Step S73), where the positive/negative determination member 106determines whether or not the flow-speed measurement range is switched.

In the flow-speed range switching determination step (Step S73), thepositive/negative determination member 106 determines whether or not theflow-speed distribution of the fluid 12 to be measured, which has beencalculated by the flow-speed distribution calculating member 67,contains any negative flow speed components. In the event thatdetermination has been made that the flow-speed distribution containsthe negative flow speed components (in a case of “NO” in Step S73), thesystem does not switch the flow-speed measurement range, following whichthe flow proceeds to the flow-speed distribution output step (Step S74),the flow-speed zero-line display step (Step S75), and the flowmeasurement processing step (Step 76).

Note that the flow-speed distribution output step (Step S74), theflow-speed zero-line display step (Step S75), and the flow measurementprocessing step (Step S76), have the same configurations as with theflow-speed distribution output step (Step S63), the flow-speed zero-linedisplay step (Step S64), and the flow measurement processing step (StepS66), shown in FIG. 26, respectively. Upon completion of the flow-speeddistribution output step (Step S74), the flow-speed zero-line displaystep (Step S75), and the flow measurement processing step (Step S76),the ultrasonic flow measurement procedure performed by the dopplerultrasonic flowmeter 10G ends.

On the other hand, in the event that determination has been made thatthe flow-speed distribution does not contain the negative flow speedcomponents in the flow-speed range switching determination step (StepS73), (in a case of “YES” in Step S73), the positive/negativedetermination member 106 requests the automatic flow-speed rangeswitching member 107 to switch the flow-speed measurement range. Then,the flow proceeds to Step S77, i.e., the flow-speed measurement rangeswitching step.

Note that Step S77, i.e., the flow-speed measurement range switchingstep has the same configuration as that of the flow-speed measurementrange switching step (Step S67) shown in FIG. 26. In Step S77, i.e., theflow-speed measurement range switching step, the automatic flow-speedrange switching member 107 switch the flow-speed measurement rangebetween the normal measurement range and the double-measurement-rangewhich allows the measurement of the positive flow speed in a flow-speedmeasurement range twice that of the normal measurement range mode. Uponcompletion of the flow-speed measurement range switching step (StepS77), the flow proceeds to Step S72. Then, the system performs theprocessing steps following the Step S72.

As described above, the doppler ultrasonic flowmeter 10G according tothe present embodiment, the flow measurement method using the dopplerultrasonic flowmeter 10G, and the flow measurement program employed forthe doppler ultrasonic flowmeter 10G, allow the user to switch theflow-speed measurement range between the normal measurement range andthe double-measurement-range, thereby enabling flow measurement in anextended flow-speed measurement range twice that of the normalmeasurement range, as necessary.

While description has been made regarding an arrangement wherein thedoppler ultrasonic flowmeter 10G includes the automatic flow-speed rangeswitching member 107 having a function for switching the flow-speedmeasurement range between the normal measurement range and thedouble-measurement-range, thereby enabling measurement of the positiveflow speed in an extended flow-speed measurement range twice that of thenormal measurement range, it is needless to say that an arrangement maybe made wherein the doppler ultrasonic flowmeter 10G has a function forswitching the flow-speed measurement range between the normalmeasurement range and the double-measurement-range, thereby enablingmeasurement of the negative flow speed in an extended flow-speedmeasurement range twice that of the normal measurement range. In thiscase, an arrangement may be made wherein in the event that thepositive/negative determination member 106 has determined that theflow-speed distribution contains no positive flow-speed components, thepositive/negative determination member 106 requests the automaticflow-speed range switching member 107 to switch the flow-speedmeasurement range to twice the flow-speed range of the normalmeasurement range mode, for measuring the negative flow, therebyenabling measurement of a backward flow in a flow-speed measurementrange twice that of the normal measurement range mode.

Note that while description has been made regarding an arrangementwherein the present embodiment is applied to the doppler ultrasonicflowmeter 10 shown in FIG. 1, having a configuration wherein thecomputer 14 reads out and executes the flow measurement PG 41H stored inthe storage member 37, whereby a combination of the Udflow unit 13,i.e., a hardware component unit, and the flow measurement PG 41H, i.e.,a software component, has the functions serving as the dopplerultrasonic flowmeter 10G, the present embodiment may be applied to thedoppler ultrasonic flowmeter 50 or the doppler ultrasonic flowmeter 60.

While description has been made regarding an arrangement wherein thedoppler ultrasonic flowmeter 10G includes the automatic flow-speed rangeswitching member 107, instead of the flow-speed measurement rangeswitching member 101, an arrangement may be made wherein the dopplerultrasonic flowmeter 10G includes both the automatic flow-speed rangeswitching member 107 and the flow-speed measurement range switchingmember 101. The doppler ultrasonic flowmeter 10G having such aconfiguration allows the user to switch the flow-speed measurement rangethrough manual switching according to a request from the user andautomatic switching.

Furthermore, the doppler ultrasonic flowmeter 10G including both theflow-speed measurement range switching member 101 and the automaticflow-speed range switching member 107 allows the user to manually switchthe flow-speed measurement range if the automatic flow-speed rangeswitching member 107 makes undesirable switching of the flow-speedmeasurement range, thereby improving use of ease as compared with thedoppler ultrasonic flowmeter 10G including the automatic flow-speedrange switching member 107 alone.

Note that the doppler ultrasonic flowmeter according to any one of theembodiments described above according to the present invention has aconfiguration wherein the flow-speed distribution of the fluid 12 to bemeasured is obtained beforehand for obtaining the flow, accordingly, thedoppler ultrasonic flowmeter according to the present invention has thefunctions serving as a flow-speed distribution meter as well as aflowmeter. Furthermore, with the doppler ultrasonic flowmeter accordingto the present invention, an arrangement may be made wherein themeasurement results of the flow-speed distribution and the flow aredisplayed on a single screen as shown in FIG. 9, or an arrangement maybe made wherein the measurement results of the flow-speed distributionand the flow are displayed on separate screens.

On the other hand, the flow measurement PG 41 employed for the dopplerultrasonic flowmeter 10 according to the present invention is notrestricted to a single program, rather, an arrangement may be madewherein separate programs form the flow measurement PG 41 as long as thecomputer 14 can execute all the procedures of the flow measurement PG41.

Furthermore, an arrangement may be made wherein the flow measurementprogram 41 or the like is stored in a recording medium for beingdistributed to the users. Note that the “recording medium” used heremeans a medium for storing an intangible program, and examples thereofinclude: a flexible disk; a hard disk; a CD-ROM; an MO (magnet-opticaldisk); a DVD-ROM; and a PD; and so forth.

Furthermore, the program such as the flow measurement PG 41 or the likestored in the storage member 37 of the computer 14 may betransmitted/received to/from other computers electrically connected tothe I/F member 40 through an electric communication line. That is tosay, a desired program can be transmitted to the other computers fromthe computer 14. Conversely, a desired program can be preinstalled ordownloaded to the computer 14 from the other computer storing thedesired program.

INDUSTRIAL APPLICABILITY

The present invention provides a doppler ultrasonic flowmeter, a flowmeasurement method using the doppler ultrasonic flowmeter, and a flowmeasurement program employed for the doppler ultrasonic flowmeter,having the advantage of enabling more correct measurement of theflow-speed distribution and more correct measurement of the flow even ifthe measured flow-speed distribution exhibits unignorableirregularities.

Furthermore, the present invention provides a doppler ultrasonicflowmeter, a flow measurement method using the doppler ultrasonicflowmeter, and a flow measurement program employed for the dopplerultrasonic flowmeter, having the advantage of automatically calculatingthe optimum value used for adjustment of measurement, which depends uponthe properties of the object to be measured.

Furthermore, the present invention provides a doppler ultrasonicflowmeter, a flow measurement method using the doppler ultrasonicflowmeter, and a flow measurement program employed for the dopplerultrasonic flowmeter, having the advantage of extending the measurementrange without extending the performance of the hardware component.

Furthermore, the present invention provides a doppler ultrasonicflowmeter, a flow measurement method using the doppler ultrasonicflowmeter, and a flow measurement program employed for the dopplerultrasonic flowmeter, having the advantage of extending the flow-speedmeasurement range in the event that determination has been made that theflow-speed distribution contains no negative flow-speed components, aswell as determining whether or not the flow-speed distribution containsany negative flow-speed components.

[Definition of Term]

The “flow measurement unit” used in this specification is unit formaking calculation as represented by the following Expression.

[Expression 2]m(t)=ρ∫ν(x, t)dA  (1)

wherein ρ represents the density of the fluid to be measured, ν(x, t)represents the velocity component (x direction) at the point in time t,and A represents the cross-sectional area through which the fluid to bemeasured passes (cross-sectional area of the tube).

Furthermore, the flow m(t) which flows within the fluid tube at thepoint in time t is represented by the following Expression bytransforming the Expression (1) described above.

[Expression 3]m(t)=ρ∫∫νx(r, θ, t)r dr dθ  (2)

wherein ν(r, θ, t) represents the velocity component at the point intime t, with a distance of r and an angle of θ, with the center of thecross-section of the tube as the center of the polar coordinate system.

1. A doppler ultrasonic flowmeter comprising: an ultrasonic transmissionmember for casting ultrasonic pulses with a predetermined frequency ontothe fluid within a fluid tube, which is to be measured, along ameasurement line from an ultrasonic transducer; a flow-speeddistribution measurement unit for receiving ultrasonic echoes reflectedfrom the measurement region due to ultrasonic pulses cast onto the fluidto be measured so as to measure the flow-speed distribution of the fluidto be measured in the measurement region; a flow measurement unit formeasuring the flow of the fluid to be measured in the measurement regionbased upon the flow-speed distribution of the fluid to be measured; anda transducer position adjusting mechanism for adjusting the relativeposition of a pair of ultrasonic transducers serving as the ultrasonictransmission member, i.e., a first transducer and a second transducer,which are disposed away one from another along the axial direction of afluid tube, wherein said transducer position adjusting mechanism has aconfiguration for adjusting the position of the pair of transducerswhile maintaining the positional relation thereof such that theultrasonic pulse beam cast from the first transducer and the ultrasonicpulse beam cast from the second transducer are orthogonal one to anotherin the measurement region within the fluid tube.
 2. A doppler ultrasonicflowmeter according to claim 1, further comprising: a firstreflected-wave receiver and a second reflected-wave receiver forreceiving ultrasonic echoes, i.e., the reflected waves from themeasurement region of the fluid tube due to ultrasonic pulses cast fromthe first transducer and the second transducer; a velocity-vectorcalculating member for calculating the velocity vectors in the directionof the ultrasonic measurement lines of the first reflected-wave receiverand the second reflected-wave receiver based upon the magnitude ofultrasonic echoes received by the first reflected-wave receiver and thesecond reflected-wave receiver, respectively; and a flow-speed vectorcalculating member for calculating the flow-speed vector of the fluid tobe measured, by calculating the vector sum of the velocity vectorscalculated by the velocity vector calculating member, wherein saidflow-speed distribution measurement unit calculates flow-speeddistribution based upon the flow-speed vectors, and wherein said flowmeasurement unit computes the flow of the fluid to be measured, basedupon the flow-speed distribution.
 3. An ultrasonic flow measurementmethod comprising: a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of a number ofreflector groups contained in the fluid to be measured; a flow-speeddistribution measurement processing step for measuring the flow-speeddistribution of the fluid to be measured, based upon the flow-speeddistribution data of the reflector groups obtained in thereflector-group-speed calculating step; and a flow measurementprocessing step for measuring the flow by further performing computationprocessing for the flow-speed distribution data of the fluid to bemeasured, wherein said flow-speed distribution measurement processingstep comprises: a flow-speed distribution calculating step forcalculating the flow-speed distribution data of the fluid to bemeasured, and the center position data of the fluid tube, by performingcomputation processing for the flow-speed distribution of thereflectors; a flow-speed distribution data output step for outputtingthe flow-speed distribution data and center position data thus obtainedin the flow-speed distribution calculating step so as to be displayed ondisplay; and an area determination step which allows the user to set adivision area where the speed of the reflector groups is calculated inthe flow-speed distribution calculating step; the area of the fluid tubebeing divided at the center position into two division areas.
 4. Anultrasonic flow measurement method comprising: a reflector-group-speedcalculating step for receiving ultrasonic echoes due to ultrasonicpulses cast onto the fluid to be measured, so as to calculate the speedof each of a number of reflector groups contained in the fluid to bemeasured; a flow-speed distribution measurement processing step formeasuring the flow-speed distribution of the fluid to be measured, basedupon the flow-speed distribution data of the reflector groups obtainedin the reflector-group-speed calculating step; and a flow measurementprocessing step for measuring the flow by further performing computationprocessing for the flow-speed distribution data of the fluid to bemeasured, wherein said flow-speed distribution measurement processingstep comprises: a flow-speed distribution calculating step forcalculating the flow-speed distribution data of the fluid to bemeasured, and the center position data of the fluid tube, by performingcomputation processing for the flow-speed distribution of thereflectors; an automatic area selecting step for automatically selectinga division area where the flow-speed distribution is calculated usingthe reflector groups; the area of the fluid tube being divided at thecenter position into two division areas; and a flow-speed distributiondata output step for outputting the flow-speed distribution data and thecenter position data obtained in the flow-speed distribution calculatingstep and the automatic area selecting step, so as to be displayed ondisplay.
 5. An ultrasonic flow measurement method comprising: areflector-group-speed calculating step for receiving ultrasonic echoesdue to ultrasonic pulses cast onto the fluid to be measured, so as tocalculate the speed of each of a number of reflector groups contained inthe fluid to be measured; a flow-speed distribution measurementprocessing step for measuring the flow-speed distribution of the fluidto be measured, based upon the flow-speed distribution data of thereflector groups obtained in the reflector-group-speed calculating step;an optimum-value setting step for calculating the optimum values of thebasic frequency f₀, the pulse repetition frequency f_(PRF), and theincident angle α; and a flow measurement processing step for measuringthe flow by further performing computation processing for the flow-speeddistribution data of the fluid to be measured, wherein saidreflector-group-speed calculating step comprises: an initial valueacquisition step for receiving the initial values of the basic frequencyf₀, the pulse repetition frequency f_(PRF), the incident angle α, at thestart of measurement; and a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of the number ofreflectors contained in the fluid to be measured, and wherein saidoptimum-value setting step includes an emission frequency reset step forresetting the emission frequency to an emission frequency f₁ so as tosatisfy the following expressions: F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di. 6.An ultrasonic flow measurement method comprising: areflector-group-speed calculating step for receiving ultrasonic echoesdue to ultrasonic pulses cast onto the fluid to be measured, so as tocalculate the speed of each of a number of reflector groups contained inthe fluid to be measured; a flow-speed distribution measurementprocessing step for measuring the flow-speed distribution of the fluidto be measured, based upon the flow-speed distribution data of thereflector groups obtained in the reflector-group-speed calculating step;an optimum-value setting step for calculating the optimum values of thebasic frequency f₀, the pulse repetition frequency f_(PRF), and theincident angle α; and a flow measurement processing step for measuringthe flow by further performing computation processing for the flow-speeddistribution data of the fluid to be measured, wherein saidreflector-group-speed calculating step comprises: an initial valueacquisition step for receiving the initial values of the basic frequencyf₀, the pulse repetition frequency f_(PRF), the incident angle α, at thestart of measurement; and a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of the number ofreflectors contained in the fluid to be measured, wherein saidoptimum-value setting step includes an incident angle reset step forresetting the incident angle to α1 so as to satisfy the followingexpressions: F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di.
 7. An ultrasonic flowmeasurement method comprising: a reflector-group-speed calculating stepfor receiving ultrasonic echoes due to ultrasonic pulses cast onto thefluid to be measured, so as to calculate the speed of each of a numberof reflector groups contained in the fluid to be measured; a flow-speeddistribution measurement processing step for measuring the flow-speeddistribution of the fluid to be measured, based upon the flow-speeddistribution data of the reflector groups obtained in thereflector-group-speed calculating step; a channel distance computingstep for computing the minimum channel distance based upon the frequencyof the ultrasonic pulses and the speed thereof; a measurement rangedisplay steps for displaying a GUI which allows the user to determinewhether or not the channel distance is set to a value obtained bymultiplying the minimum channel distance by an integer, thereby allowingthe user to set the measurement region to a value obtained bymultiplying the minimum measurement region by an integer; a channeldistance changing step for changing the channel distance to a valueobtained by multiplying the minimum channel distance by an integer,according to instructions of the user; and a flow measurement processingstep for measuring the flow by further performing computation processingfor the flow-speed distribution data of the fluid to be measured.
 8. Anultrasonic flow measurement method comprising: a reflector-group-speedcalculating step for receiving ultrasonic echoes due to ultrasonicpulses cast onto the fluid to be measured, so as to calculate the speedof each of a number of reflector groups contained in the fluid to bemeasured; a flow-speed distribution measurement processing step formeasuring the flow-speed distribution of the fluid to be measured, basedupon the flow-speed distribution data of the reflector groups obtainedin the reflector-group-speed calculating step; a channel distancecomputing step for computing the minimum channel distance based upon thefrequency of the ultrasonic pulses and the speed thereof; a measurementrange calculating step for calculating the measurement range based uponthe minimum channel distance thus computed; a channel distance changingstep having a function for determining whether or not the channeldistance is to be set to a value obtained by multiplying the minimumchannel distance by an integer, thereby allowing the system toautomatically change the channel distance; and a flow measurementprocessing step for measuring the flow by further performing computationprocessing for the flow-speed distribution data of the fluid to bemeasured.
 9. An ultrasonic flow measurement method comprising: areflector-group-speed calculating step for receiving ultrasonic echoesdue to ultrasonic pulses cast onto the fluid to be measured, so as tocalculate the speed of each of a number of reflector groups contained inthe fluid to be measured; a flow-speed distribution measurementprocessing step for measuring the flow-speed distribution of the fluidto be measured, based upon the flow-speed distribution data of thereflector groups obtained in the reflector-group-speed calculating step;a flow-speed distribution output step for outputting the relationbetween the flow-speed distribution of the fluid to be measured and thedistance in the direction of the measurement line ML, in the form of animage on a screen; a flow-speed zero-line display step for superimposinga fluid-speed zero line on the flow-speed distribution output in theform of an image on a screen in the flow-speed distribution output step;a flow-speed measurement range switching determination step which allowsthe user to determine whether or not the flow-speed measurement range isswitched; a flow-speed measurement range switching step for switchingthe flow-speed measurement range to twice that of the normal measurementrange, for measuring the positive flow speed according to theinstructions of the user; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured.
 10. Anultrasonic flow measurement method comprising: a reflector-group-speedcalculating step for receiving ultrasonic echoes due to ultrasonicpulses cast onto the fluid to be measured, so as to calculate the speedof each of a number of reflector groups contained in the fluid to bemeasured; a flow-speed distribution measurement processing step formeasuring the flow-speed distribution of the fluid to be measured, basedupon the flow-speed distribution data of the reflector groups obtainedin the reflector-group-speed calculating step; a flow-speed rangeswitching determination step which allows the user to determine whetheror not the flow-speed measurement range is switched; a flow-speeddistribution output step for outputting the relation between theflow-speed distribution of the fluid to be measured, and the distance inthe direction of the measurement line ML, in the form of an image on ascreen; a flow-speed zero-line display step for superimposing aflow-speed zero line on the flow-speed distribution output in the formof an image on a screen in the flow-speed distribution output step; aflow-speed measurement range switching step for switching the flow-speedmeasurement range to twice that of the normal measurement mode accordingto the instructions of the user for measuring the positive flow speed;and a flow measurement processing step for measuring the flow by furtherperforming computation processing for the flow-speed distribution dataof the fluid to be measured.
 11. A computer readable medium havinginstructions encoded therein that when executed by a processor in anultrasonic flowmeter perform steps comprising: a reflector-group-speedcalculating step for receiving ultrasonic echoes due to ultrasonicpulses cast onto the fluid to be measured, so as to calculate the speedof each of a number of reflector groups contained in the fluid to bemeasured; a flow-speed distribution measurement processing step formeasuring the flow-speed distribution of the fluid to be measured, basedupon the flow-speed distribution data of the reflector groups obtainedin the reflector-group-speed calculating step; a flow measurementprocessing step for measuring the flow by further performing computationprocessing for the flow-speed distribution data of the fluid to bemeasured, wherein said flow-speed distribution measurement processingstep comprises: a flow-speed distribution calculating step forcalculating the flow-speed distribution data of the fluid to bemeasured, and the center position data of the fluid tube, by performingcomputation processing for the flow-speed distribution of thereflectors; a flow-speed distribution data output step for outputtingthe flow-speed distribution data and center position data thus obtainedin the flow-speed distribution calculating step so as to be displayed ondisplay; and an area determination step which allows the user to set adivision area where the speed of the reflector groups is calculated inthe flow-speed distribution calculating step; the area of the fluid tubebeing divided at the center position into two division areas, and saidreflector-group-speed calculating step, said flow-speed distributionmeasurement processing step, and said flow measurement processing stepbeing executed by the processor.
 12. A computer readable medium havinginstructions encoded therein that when executed by a processor in anultrasonic flowmeter perform steps comprising: a reflector-group-speedcalculating step for receiving ultrasonic echoes due to ultrasonicpulses cast onto the fluid to be measured, so as to calculate the speedof each of a number of reflector groups contained in the fluid to bemeasured; a flow-speed distribution measurement processing step formeasuring the flow-speed distribution of the fluid to be measured, basedupon the flow-speed distribution data of the reflector groups obtainedin the reflector-group-speed calculating step; and a flow measurementprocessing step for measuring the flow by further performing computationprocessing for the flow-speed distribution data of the fluid to bemeasured, wherein said flow-speed distribution measurement processingstep comprises: a flow-speed distribution calculating step forcalculating the flow-speed distribution data of the fluid to bemeasured, and the center position data of the fluid tube, by performingcomputation processing for the flow-speed distribution of thereflectors; an automatic area selecting step for automatically selectinga division area where the flow-speed distribution is calculated usingthe reflector groups; the area of the fluid tube being divided at thecenter position into two division areas; and a flow-speed distributiondata output step for outputting the flow-speed distribution data and thecenter position data obtained in the flow-speed distribution calculatingstep and the automatic area selecting step, so as to be displayed ondisplay, and said reflector-group-speed calculating step, saidflow-speed distribution measurement processing step, and said flowmeasurement processing step being executed by the processor.
 13. Acomputer readable medium having instructions encoded therein that whenexecuted by a processor in an ultrasonic flowmeter perform stepscomprising: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; an optimum-value setting step for calculating the optimum valuesof the basic frequency f₀, the pulse repetition frequency f_(PRF), andthe incident angle α; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured, wherein saidreflector-group-speed calculating step comprises: an initial valueacquisition step for receiving the initial values of the basic frequencyf₀, the pulse repetition frequency f_(PRF), the incident angle α, at thestart of measurement; and a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of the number ofreflectors contained in the fluid to be measured, and wherein saidoptimum-value setting step includes an emission frequency reset step forresetting the emission frequency to an emission frequency f₁ so as tosatisfy the following expressions: F₀≧4V₀·sin α; and f_(PRF)≦Cw/2Di, andsaid reflector-group-speed calculating step, said flow-speeddistribution measurement processing step, said optimum-value settingstep, and said flow measurement processing step being executed by theprocessor.
 14. A computer readable medium having instructions encodedtherein that when executed by a processor in an ultrasonic flowmeterperform steps comprising: a reflector-group-speed calculating step forreceiving ultrasonic echoes due to ultrasonic pulses cast onto the fluidto be measured, so as to calculate the speed of each of a number ofreflector groups contained in the fluid to be measured; a flow-speeddistribution measurement processing step for measuring the flow-speeddistribution of the fluid to be measured, based upon the flow-speeddistribution data of the reflector groups obtained in thereflector-group-speed calculating step; an optimum-value setting stepfor calculating the optimum values of the basic frequency f₀, the pulserepetition frequency f_(PRF), and the incident angle α; and a flowmeasurement processing step for measuring the flow by further performingcomputation processing for the flow-speed distribution data of the fluidto be measured, wherein said reflector-group-speed calculating stepcomprises: an initial value acquisition step for receiving the initialvalues of the basic frequency f₀, the pulse repetition frequencyf_(PRF), the incident angle α, at the start of measurement; and areflector-group-speed calculating step for receiving ultrasonic echoesdue to ultrasonic pulses cast onto the fluid to be measured, so as tocalculate the speed of each of the number of reflectors contained in thefluid to be measured, and wherein said optimum-value setting stepincludes an incident angle reset step for resetting the incident angleto α1 so as to satisfy the following expressions: F₀≧4V₀·sin α; andf_(PRF)Cw/2Di, and said reflector-group-speed calculating step, saidflow-speed distribution measurement processing step, said optimum-valuesetting step, and said flow measurement processing step being executedby the processor.
 15. A computer readable medium having instructionsencoded therein that when executed by a processor in an ultrasonicflowmeter perform steps comprising: a reflector-group-speed calculatingstep for receiving ultrasonic echoes due to ultrasonic pulses cast ontothe fluid to be measured, so as to calculate the speed of each of anumber of reflector groups contained in the fluid to be measured; aflow-speed distribution measurement processing step for measuring theflow-speed distribution of the fluid to be measured, based upon theflow-speed distribution data of the reflector groups obtained in thereflector-group-speed calculating step; a channel distance computingstep for computing the minimum channel distance based upon the frequencyof the ultrasonic pulses and the speed thereof; a measurement rangedisplay step for displaying a GUI which allows the user to determinewhether or not the channel distance is set to a value obtained bymultiplying the minimum channel distance by an integer, thereby allowingthe user to set the measurement region to a value obtained bymultiplying the minimum measurement region by an integer; a channeldistance changing step for changing the channel distance to a valueobtained by multiplying the minimum channel distance by an integer,according to instructions of the user; and a flow measurement processingstep for measuring the flow by further performing computation processingfor the flow-speed distribution data of the fluid to be measured, saidrespective steps being executed by the processor.
 16. A computerreadable medium having instructions encoded therein that when executedby a processor in an ultrasonic flowmeter perform steps comprising: areflector-group-speed calculating step for receiving ultrasonic echoesdue to ultrasonic pulses cast onto the fluid to be measured, so as tocalculate the speed of each of a number of reflector groups contained inthe fluid to be measured; a flow-speed distribution measurementprocessing step for measuring the flow-speed distribution of the fluidto be measured, based upon the flow-speed distribution data of thereflector groups obtained in the reflector-group-speed calculating step;a channel distance computing step for computing the minimum channeldistance based upon the frequency of the ultrasonic pulses and the speedthereof; a measurement range calculating step for calculating themeasurement range based upon the minimum channel distance thus computed;a channel distance changing step having a function for determiningwhether or not the channel distance is to be set to a value obtained bymultiplying the minimum channel distance by an integer, thereby allowingthe system to automatically change the channel distance; and a flowmeasurement processing step for measuring the flow by further performingcomputation processing for the flow-speed distribution data of the fluidto be measured, said respective steps being executed by the processor.17. A computer readable medium having instructions encoded therein thatwhen executed by a processor in an ultrasonic flowmeter perform stepscomprising: a reflector-group-speed calculating step for receivingultrasonic echoes due to ultrasonic pulses cast onto the fluid to bemeasured, so as to calculate the speed of each of a number of reflectorgroups contained in the fluid to be measured; a flow-speed distributionmeasurement processing step for measuring the flow-speed distribution ofthe fluid to be measured, based upon the flow-speed distribution data ofthe reflector groups obtained in the reflector-group-speed calculatingstep; a flow-speed distribution output step for outputting the relationbetween the flow-speed distribution of the fluid to be measured and thedistance in the direction of the measurement line ML, in the form of animage on a screen; a flow-speed zero-line display step for superimposinga fluid-speed zero line on the flow-speed distribution output in theform of an image on a screen in the flow-speed distribution output step;a flow-speed measurement range switching determination step which allowsthe user to determine whether or not the flow-speed measurement range isswitched; a flow-speed measurement range switching step for switchingthe flow-speed measurement range to twice that of the normal measurementrange, for measuring the positive flow speed according to theinstructions of the user; and a flow measurement processing step formeasuring the flow by further performing computation processing for theflow-speed distribution data of the fluid to be measured, saidrespective steps being executed by the processor.
 18. A computerreadable medium having instructions encoded therein that when executedby a processor in an ultrasonic flowmeter perform steps comprising: areflector-group-speed calculating step for receiving ultrasonic echoesdue to ultrasonic pulses cast onto the fluid to be measured, so as tocalculate the speed of each of a number of reflector groups contained inthe fluid to be measured; a flow-speed distribution measurementprocessing step for measuring the flow-speed distribution of the fluidto be measured, based upon the flow-speed distribution data of thereflector groups obtained in the reflector-group-speed calculating step;a flow-speed range switching determination step which allows the user todetermine whether or not the flow-speed measurement range is switched; aflow-speed distribution output step for outputting the relation betweenthe flow-speed distribution of the fluid to be measured, and thedistance in the direction of the measurement line ML, in the form of animage on a screen; a flow-speed zero-line display step for superimposinga flow-speed zero line on the flow-speed distribution output in the formof an image on a screen in the flow-speed distribution output step; aflow-speed measurement range switching step for switching the flow-speedmeasurement range to twice that of the normal measurement mode accordingto the instructions of the user for measuring the positive flow speed;and a flow measurement processing step for measuring the flow by furtherperforming computation processing for the flow-speed distribution dataof the fluid to be measured, said respective steps being executed by theprocessor.